88 XJ rough idle starting to go crazy

[jeepcrazy5722]

All of a sudden i have developed a rough idle almost stalled on me on the way home the other night when i came to a stop. Replaced the plugs and fuel filter. Recently (about a year ago) replaced all injectors, plug wires, ignition coil, distributor, cap/rotor, TDC sensor. Thought it could be the exhaust but not sure and don't want to spend then money if it is something else. Any ideas would greatly help. Thanks for the help

 

[MudderChuck]

A few things that come to mind are a sticky dirty IAC. I've had good luck removing them and cleaning everything up, the IAC plunger/piston and the seat in the TB. Then letting a little spray oil run behind the IAC piston/plunger. Don't try moving the piston/plunger on the IAC, you may damage it (tiny electric motor in there with a fine jack shaft) or worse yet launch it (there is a spring behind it).
Of the EGR is sticking open it will also idle really rough and stall sometimes when braking. The quick test is to unplug the EGR vacuum line and plug it and see what happens. Sometimes the EGR sticks open and this doesn't help. The vacuum solenoid needs power, it defaults open and if it is open during idle it will lug and possibly stall the motor.
Vacuum line to the MAP can also do this. the vacuum line sometimes rubs through on the bottom where you can't see it.
Just a few things to check, though it can be other things.

 

[jeepcrazy5722]

I'll give that a try tonight and see if that works.

 

[bobcat481]

I agree with ChuckerMudd . IAC or vac. leaks could be culprit. To do a quick check for vac. leaks "spritz" a little starting fluid here and there around the lines and connections. If you hear the rpm's pick up a little, investigate that area a little further.

 

[jeepcrazy5722]

I replaced the TPS, so far so good, i took it on a test drive and purrs like a kitten, i will see what happens in the next couple of days, thanks for the suggestions.

 

[MudderChuck]

You may be home free, TPS was next on the list. I'd check the ground wire from the TPS, goes through a number of connectors and eventually ends up at a ground ring on the dipstick holder. An ohm test is best, a good ground on the TPS a must. I always scrub out the TPS connector with a good contact spray.