coon3y

I have a 1990 Cherokee Laredo, 4.0 straight 6 engine, automatic transmission, ~250,000 miles.

It drove great until it got cold outside, then started having trouble.
At first, I had problems with the RPMs jumping 500-1000rpm sporadically while driving, as if having a seizure. Aside from that it was driving fine, until it started having electrical issues. Suddenly, running the headlights and heater at the same time was too much strain and the jeep would stall out if you tried to have two things on at once. Even just headlights and wipers. Or Heater and Radio. Bad news. About a week later, it stalled out on me and wouldn't start back up. Per the suggestion of a friend who worked at a local car parts store for quite some time, the following things were replaced (in order)

-battery
-alternator
-MAP Sensor
-Throttle Position Sensor
-Crankshaft Position Sensor

After replacing the throttle position sensor, the jeep would cold start, stay running for 5-10 minutes, then stall out. Drove fine until it got to operating temperature, and stalled out. Would not start again, had to tow home.

I had a mechanic replace the crankshaft position sensor, which was damaged, and the vehicle still would not stay running. Engine would crank, turn over, and rev up to about 2300rpm, then stall.

The mechanic got to looking around and under the dash found what he called a car alarm, which I have found to be the Emission Maintenance Reminder. He unplugged it, removed the negative battery terminal, let it sit for a couple minutes, then reconnected the battery, reconnected the EMR, and the jeep started and ran, better than ever. New issue: Emission Maintenance light is on. Mechanic says not to worry about that.

Three days of blissful driving with no trouble whatsoever, and last night we get 3 inches of snow. Driving home, the engine stalls and won't start. It cranks, turns over, revs up to ~2300 rpm, and stalls.

Being that the Emission Maintenance light is on, could it be that I need to replace the EMR and the Oxygen sensor? Or is there something else that could be causing my troubles?

Any and all help is appreciated, I'm tired of buying parts that don't fix my problem.

VTJeep

i hate issues that are kinda random like this... just for kicks, make sure all fluids are good... there are still random things like the cap/rotor, and o2 sensors, the coil. idk about '90's but these were all things that went towards fixing this weird hesitation in my 99xj... i dont think ther is an IAC valve on yours, buit thats another part. have you had the TB cleaned... compression test, blow out gas lines... just throwin ideas out!