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1990, with basically stock 4.0. Recently upgraded to Volvo 4 hole injectors. Runs great, better gas mileage. Most of my driving is sea level to 1000 feet. Went to Eastern Washington and crossed one pass at 5400 ft and into a back-country lake at 2200+ feet. On both I noticed a definite loss of power and overheating. The route into the lake was only 2200 to 4000 feet, but was done slowly on a rough, rocky road. The initial 1000 feet was very steep and overheated to boiling over. The pass was highway speeds, 60 mph, and overheated, but not to the red-line. Dropped off as soon as I started downhill and dropped rpm. I noticed a definite lack of power each time. I reset the ECM after adding the new injectors, and it's been running great, but wonder if I could be running lean, particularly at altitude. Reset ECM again, other suggestions??? Next step will be upgrading to a open (real radiator and cooling) system.

I have an '86 Comanche 2.5L with Throttle Body Injection and a AX4, 4-speed manual. The engine is not the original Comanche engine, but one from a YJ Wrangler from what I would assume is similar in year and function. Anyway, I was driving it the day before last to work and it was doing fine until it warmed up. All of a sudden, it just acted like it wasn't getting gas when I pressed the accelerator. It idled back down and was running rough, but as soon as I tried to give it gas, it would spit/sputter and bog down. It shut off on its own, so I gave it a few seconds and then I started it back up and the problem went away, for a little while anyway. I got about 2 miles further down the road and then the same thing. That time, I cut the engine off and restarted it about 10 seconds later. I made it all the way to work from then on without hesitation. On the way home from work, the same thing happened 3 more times. Anyone have any ideas on what this could be caused by? It has new spark plugs, a clean air filter, fuel injector cleaner and Iso-heet (water remover) in the gas. Edit... I took it for a test drive today with my dad to see what he thinks, and it did it about 4 times just going a couple miles down the street. We both feel as though it something fuel related or sensors starving it of gas. I have noticed a pattern, however. When it begins these spells of bogging down, I will turn of the engine and start it again while I'm coasting (did that all 4 times during today's drive). Once it's been restarted, it runs and drives perfectly fine for a little while until the issue arises again. It's the damndest thing because I don't have a clue how to begin sourcing the problem... I imagine just strictly looking at the fuel system, there are really only four main components: Fuel pump, fuel filter, pressure regulator and TB injector. The FP seems to prime fine and I can hear it running when idled and what not, though I haven't tested it for the 14-15 psi pressure that's needed. The fuel filter looks to have been recently replaced by the previous owner as it appears new from the outside. The TB injector seems to be spraying good and in a conical fashion. I haven't put a vacuum meter on the regulator, but that's next. Also, it's been suggested on CherokeeForum that it could be my TPS. I will be checking that with my digital multimeter. The O2 sensor appears to have been replaced by the PO. So, as far as sensors go, I don't know what else could alter the A/F ratio. I guess the most confusing part of it all is that when I cut it off and restart the engine, it runs fine for a little while. It's very random when the symptom occurs. Anyway, sorry for the long post, but I really need to figure it out soon because I'm about to stop driving my XJ to swap in a stroker. Any help or advice on this MJ issue would be greatly appreciated. Forgot to mention, the PO removed the cat and just ran a pipe to the muffler, so a clogged cat can't be an issue. Sorry if speaking of this is against forum rules, I am simply mentioning it to eliminate that as a potential issue...

This just started yesterday and I'm not quite sure where to begin. When i was driving from a complete stop i put it in 1st gear and it was fine but as the RPMs got higher it seemed as if it was struggling to keep the power so i switched to 2nd and the same thing happened. Fine at first but struggled to hold the power. ANY ideas please help. I replaced the CPS a year ago. spark plugs are good. I'm not quite sure what else to do

I bought my 87 comanche about six months ago at 165k and within the first month i had to replace the slave cylinder which was a lot more work than it shouldve been on account its internal. It ran decent over the summer but now first when I start her up it gets to some high RPMs. while driving there is a big loss of power and whats seems to be a horrible vaccum leak.It sounds like a lot of air is being blown and also whenever the engine is under heavy load air will come out of the defrost wheather the switch is on or off (the other vents don't work). ive checked all the hoses and replaced attachments, checked the resovior in the bumper but can't find anything that screams at me. I recently had to take the truck to a shop in to a shop to fix some wiring for my tailights that I didnt have time for and I asked them to see if they could find a vacuum leak. They fixed the lights and just told me my 02 sensor shorted out. I had my doubts this was the problem but replaced it anyway. Didnt make any difference it still runs like crap. If anyone has had this problem or has any ideas how to pinpoint this issue I would graetly appreaciate it. -jake