Hey Gaash2. Well, i took a look at your save, and honestly i do not know why you think Pacal is far ahead. You have 10 cities more. Of course you have no choice but to raze his city (Chicen Itza). Your invading force is quite strong but i am not sure if it will be sufficient to take out Pacal completely, it might be. It lacks siege units though, you need to get to get to Artillery. Also get some aircraft carriers with bombers. Then of course you can win easily Space or Domination. 24 cities are more than enough to win space.
I also recommend watching "Lain Civ 4 deity" and "Chris67132" on youtube. They are really good Civ 4 players who can beat the game on deity difficulty. I did learn most of the games from their Let`s Plays.
Then i want to adress your mistakes from my point of view. Maybe not all of them might be 100% accurate, there are better players in this forum than me.
Hopefully you can understand that as contructive criticism. I made 20 points and then there is still a lot to improve.
1) Where is the University of Oxford. It needs to be build in your capital like 500 -700 years ago.
2) 9 workers? you need asap more workers to build railroads and make workshops and farms. Get railroads on the tiles with hill mines to get extra hammer.
1.5 workers /city is a good rule of thumb.
3) Change your civics. Your cities have health issues, swap out of State Property (SP) into environmentalism. then build some Health buildings and switch back to SP.
Get out of Representation, dont know why you are not in Police State when you are going into a war with Pacal. Or just buy Hamas and Grocers etc, with Universal
Suffrage.
4) You should probabaly switch into Universal Suffrage and start buying building for your cities. I see so many cities lacking the essential building, and i EVEN SEE ONE CITY WITH
ONLY A FORGE AT 1858 AD. Fix this. You need to buy factories, coal and water plants, libraries, universities, Hamams (great building , one of the best UB in the game)
No idea why you do not build it. GRANARIES, best building in the game, you need like 6000 years to build them, maybe that is a bit bad.
5) Stop running so many specialists. They are very inefficient, even with representation, assign them to wrok tiles instead. You do not need any more GPP.
6) Stop working the coast. Very bad tiles unless of course you have fish, clamp etc. You have biology it is time to build farms and mines especially in Sansum.
7) NATIONAL EPIC???? Of course so late into the game you don t need it anymore, but you need to build it like at least 1000- 1400 years earlier.
8) Why you starve Timbuktu for GPP? Another Great Person so late into the game will be useless unless you found a corporation. Sids Sushi is still avilabe for example.
Usually it is better to work tiles and grow your cities as high as possible.
9) Don t work scientists in your capitol Istanbul. Assign them to work tiles, grab tiles from Istanbuls surrounding cities to your capitol. For example edirne to the north
works a town but only has a library (+25 % extra beakers for science). Istanbul has an academy, a library, an university, and a observatorium (+125% extra beakers for
science) . Meaning your town tile only proudces 10 BpT instead of 18 BpT (Beakers per Turn) if it would be worked by Istanbul.
10) The concept i mentioned above is to have "Helper cities" around your capitol, which grow cottages for your capitol, and later when the capitol grows in Size, it takes
back the tiles because you build like the University of Oxford and an academy there. Your capitol wants to work as many commerce (or hammer tiles) as possible!
11) Jewish temples. The Apostolic Palace was build in Judaism, Granting you 1 extra happiness and more important +2 Hammers. So late into the game most cities only
need 2-3 turns to build a Jewish temple or just buy them. With a factory and a forge and coal plants you get + 4 hammers for bascially free.
12)!Of course this is just a guess. But i think you lack understanding of proper empire management. There are basic buildings you want to have in every city.
Granary, Forge, Library and Courthouse. I would build these buildings in nearly every city, also a barracks is usually a good investment if you use slavery to produce
troops. Then of course you choose your 6 best cities (the ones with either best commerce or most hammers) and build 6 universities. You don t need more usually
since 200 hammers for this building is quite a lot. Then you get to build Oxford in the city with the most commerce. Usually but not always your capitol.
13) The National Epic. You usually need 1 city with lots of food (e.g.irrigated corn and wheat) and some decent hammers to build the national epic. In most of the games.
The fact that you did not build it and we already have 1858 A.D i a major mistake.
14) Especially in this game. Suleiman has the trait "organised" and "expansive" which lets you build courthouses and granaries and also factories at double speed.
Make use of this absolutely overpowered leader and build these 3 buildings in nearly every city.
15) As soon as you get to CS ( Civil Service) you want to build farms to food tiles (corn, wheat, rice) in order spread irrigation to these tiles, this gives +1 food.
16) Food is the most important resource. Especially when you have granaries, food outshines hammers and commerce, since you can store 50% food which lets your
cities regrow faster after whipping or drafting.
17) Build factories + Coalplants as soon as possible , you can use slavery to whip it in cities with low hammers.
18) Especially lategame the combination of State Property + Biology Farms (4 food) + Caste Syste + workshops is quite powerful. Also build watermills on the river tiles.
19) Stop building Wealth in your cities, you need to get granaries, forges, factories and coal plants in your cities. basic infrastructure.
20) Your plan was to attack Pacal, usually especially in Immortal/Deity difficulty you can t do 2 things at the same time, e.g. researching and building troops.
Just focus on how you want to attack. In this case with Infantry / transport ships + Siege units. The fact that you attack with only like 9 canons is quite bad.
Instead of teching unneccessary techs like medicin , plastics , electricity is quite bad. Instead get Artillery and you may be able to attack like 100 years earlier.
After this long rant, i will draw a line here

. To be honest i am quite amazed that you can win this game on Immortal difficulty with so many mistakes.
Hopefully some tips i stated will help you make better decisions in future games. Also i hope some better players from the forums can maybe correct my advices or give
other helpful advice.