Hello to all, this is an amazing forum with a ton of info. I need a little help with this Jeep I just bought. Sometimes it runs perfectly, most of the time however it will stumble at idle, almost turn off and then rev back up.(it's never actually shut off) It also has a tendency to bog down when I give it to much gas. I've been dealing with this problem for over a week now and have done numerous searches on this site and have followed instructions I came across on those searches. I picked up this XJ for a 1000 bucks about ten days ago. It was smog'd and registered and ran good enough. Now I want to get it running perfect(as perfect as 180k can be).
It's an 87 4.0L renix. I've done the plugs cap and rotor, the coolant sensors, the fuel filter. I've tried switching out the IAC and TPS with no change. The O2 sensor looks to be brand new(might have needed it for the smog). With the car on it's at 14.4 volts and fuel pressure is 31PSI regulated 38PSI W/out. Most of the time I have to tap the gas peddle to start it.

Any ideas?

I should also mention the fuel filter made the biggest improvement. Everything else was as if I didn't change anything.