Need help guys 2.3ng

[xxErix]

Hello

So, I daily drive a Audi coupe 80 B3 2.3ng, 1990, i have changed bunch of parts, and basically just doing it up to the way I see it... it has been running a bit rich, and idle has been a bit rough but nothing crazy.
But two days ago, I went for a shopping trip, and then outside the store, I started it, and it was barely running, and when I pressed the throttle, it just died, and after a few times trying it, worked fine. (also I noticed that the radiator FAN has been on all the time, I think its the coolant temp sensor, which has been ordered)
So for the rest of the day its running fine, until same thing happened in evening.
Yesterday, again seem to be okay for most part, untill later on in a day, and when driving home in evening, I noticed that the throttle is not as responsive, like I will press it half way, and it will barely pick up, and then when i press it more, it just goes almost like wide open.

anyone has experienced anything like it? any help would be appreciated,

also anyone know where I could possibly get Kjet tunned so its not running as ritch?

Thank you