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Discussion Starter · #1 ·
I have a 1990 YJ with the 2.5L 4 banger that starts very easily and will fast idle for about 10-15 seconds and then it will slowly slow down and die. I then re-start it and it will do the same thing but a little quicker this time. If I hold my foot on the gas and hold it up to about 1500 rpm it will surge about 300 rpm. If I sit there and let it warm up for about 3 minutes it will speed up the rpm a little and then it will stay running and run perfect from then on.
I just bought this without a transmission, so I didn't have a chance to check out the motor, it had been sitting for 1-1 1/2 years, and I was assured by the previoius owner that it ran great when it was parked.

It was doing this even after warm up until I replaced the MAP sensor and now it's only when I first start it up. I have also replaced the fuel filter, and put a new intake/exhaust gasket on since it was leaking exhaust pretty badly.

Any ideas what could be causing this?
 

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need to check the throttle body and see if it is clean, mine was doing the same thing and was sitting for about as long as yours. we dumped about a half of can of carb cleaner down it and it cleaned it up alittle and it is know idleing. something else to check is vaccums. hope this helps.
 

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Discussion Starter · #3 ·
carb cleaner

Thanks, I'll give that a try. I'm assuming you meant half of a spray can of carb cleaner, right?
I've already went through all of the vacuum lines, and replaced just about every one of them.
 

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Discussion Starter · #5 ·
no hose either

I also noticed that it's missing the silver flexible hose that goes from the exhaust manifold to the airbox. Would this cause my problem?
 

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Not sure about that one. Did you give your throttle body a good cleaning out? Spray that stuff on there very liberally, linkages as well. Clean all the outer workings as well, as they tend to get sticky after awhile.
 

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CRISCO81 said:
I also noticed that it's missing the silver flexible hose that goes from the exhaust manifold to the airbox. Would this cause my problem?
I'm glad you got it running, but the answer to this is no.
 

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Discussion Starter · #10 ·
Not yet.....

Well I just thought it was fixed. The first time I drove it after cleaning the throttle body with carb cleaner it worked great. But the next time I drove it it was back to it's old self again. I had the same thing happen after I put on a new map sensor, it worked great the first time I drove it, but stalled the second time. If I let it warm up for a couple of minutes it works perfect, but until it warms up, it will stall.
Any other ideas?
 

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Discussion Starter · #11 ·
I'm still having this problem. I have now taken off the EGR valve and blocked it off and it didn't change it one bit.
It is very consistant, just like clockwork, it will slowly slow down and die, and if I hold my foot on the gas and hold it up to 2000 rpm it will surge up and down, just like you're turning off the key and back on. But after about 3 minutes it will quit doing this and run perfectly.
Any ideas?
 
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