just towed, help... ('98)

On parkway, engine begins straining to maintain speed, finally can't get above thirty, idles like new though.

Towed home, idling fine in my garage, but even under no load major breaking up when throttled.

I began disconnecting electrical connectors that attach to throttle body, then the one that sits parallel with valve cover, four pin connector, black cylindrical part that attaches to metal rectangular piece that attaches directly to throttle body, seems to control rectangular vent in throttle body, when I disconnected that, it made absolutely no change in way motor ran.

Until I get out of this hysterical state, could someone tell me what this part is and if the actions I took maybe proved it died?

Symptoms been on and off last fifty miles or so, thought it was the tranny because all of the sudden tranny (aw4) would kick into passing gear for no reason and the k&n was making a funky growling intake noise.

Thanks...

It sounds like you unplugged the Idle Air Controller. It will make no difference when you unplug it. With it unplugged, the computer can't compensate for the idle under different environmental conditions.

With what you describe, I would guess it is the MAP sensor or a plugged CAT. The TPS would be a distant third.

I replaced the front and rear 02 sensors about 300 miles ago, preventive maintenance.

I'll look into your suggestions, but if the IAC was inplugged, why would the idle stay smooth as silk!?!

Not good as a diagnostician, thanks for the reply...

sounds like the the cat to me.

IAC had adjusted for the idle, and stays at that setting when it unplugged.

Drill a small hole in front of the cat, in the ex. and see if it improve. if it does the cat is bad.........how many miles on it?

about 117k miles...

Hmmm, get you drill out, put a 3/8 hole in the pipe............if it don't change any thing, it will be simple to weld back up have a ex shop do for ya cheep!

Is it throwing any codes?

Crank Position Sensor?

check your fuel pressure and flow

just changed cps 200 miles ago

oem fuel pump maybe 1k ago

I have to go to Florida tommorow to pick-up a second car I have there until I can sort my xj fiasco in NY. Sort of a pre-planned vacation without knowing the xj took a dump, really puts a damper on the family vacation.

I AM EXTREMELY APPRECIATE of all the suggestions, when I drive this monstrosity back to NY about 12/31, I'll ressurrect the thread and start following the advice you guys gave me.

God Bless and have a safe, healthy, and happy holiday season.

Thank You!!!