Have a 90 model xj 4.0 auto. I have replaced tps sensor idel air, o2 and map. Still having the same problem. Driving and when I let off the gas it acts like it wants to die and other times it's fine. But when I hit the brakes to slow down or stop it will die unless I keep one foot on gas. Any ideas where to start will help a lot. Possible vac leak or what? Love my jeep but can't enjoy driving it because of this

 

i have the same problem with mine. could it be a bad fuel pump? because i had some old gas in mine

 

Have you checked for any codes? Or is that one o' those Renault-Bendix animals that has no CEL? If it is, then you probably need to clean all the grounds/connections you can find.
*Also, you said "when I hit the brakes to slow down or stop it will die unless I keep one foot on gas". Is it an automatic? Have you tried shifting into neutral when coming to a stop to see if it still wants to die?

 

Yes it's auto. Makes no difference

 

'90 was the last year of the RENIX ignition system so yes, it's a RENIX system.

I would recommend using this guide to run diagnostics on all engine sensors, especially the one devoted to your CPS. I would also recommend following the advice offered by kjc and refresh all grounds as this is a common problem with RENIX-era ignition systems.

You should also test fuel pressure at the fuel rail, if you don't have a fuel pressure gauge, they can be rented from most big-box auto parts shops.

 

What should the pressure be? I did notice a strange sound coming from fuel pump so it could be weak. But I will check the pressure first

 

This will help...

http://www.lunghd.com/Tech_Articles/...iagnostics.htm

 

Just put new fuel filter and a new crank position censor on and did the fuel pressure test and everything is spot on. So any other ideas?

 

So, it basically sounds like your jeep just won't idle, yes? Did you find any vacuum leaks? Also, you said you replaced the IAC and the TPS.. I don't know Renix models, but isn't it required to adjust/calibrate one or both of those sensors when they're replaced?