When I start m truck, it will idle up high (not too high), just high enough to get my vacuum up to like 18-20 inches. This will last for about a minute. The, the system acts like it's searching for the best idle. The RPMs will slowly start to cycle down until thr truck dies (takes about 5 mintes after starting to do this). If I restart the truck, the same thing will happen. There is no problem restarting, she fires right up.

If I drive away cold, the engine will pulse when I idle. Like, if I roll up to a stop sign, the engine will surge or pulse about once a second, and my vacuum will be really crappy, like 13 or 15 inches. There is a slight hesitation when I take off from the line, like the truck is going to die. Then it picks up.

After about 2 miles, the truck starts to warm up and the idle goes all warm and fuzzy. When I got home friday (it was about 70 degrees outside) the einge was nice and warm. I pulled into the driveway and the engine was purring with a failry low idle and sitting at 20 incches of vacuum.

I am suspecting the IAC or the engine temperature sensor. I don't really know why the IAC would care what temperature I am at (seems like it would work poorly no matter what it if was cruddy). I replaced the IAC last summer. I am planning on cleaning it, but I really don't think the symptoms fit that bill.

Does anyone else know what I should try? I have checked my vacuum lines. They are all new, even the lines on the TB and the line back to the tranny. I replaced my upper intake gasket and my TB gasket the other day, so they are fine. The fact that I can get the 20 inches of vaccum when the engine is warm makes me think it's not a vacuum leak.

Any ideas?

 

I would test the temp sensor that tells the computer if the engine is warm or not. Sounds like the computer thinks the engine is warm so it isn't running rich enough to keep running when cold.

 

I just checked the ECT and the ACT and they both seem fine. I checked them at cold and then again when the engine had warmed up.

I noticed that my injector for #2 (the front driver's side) cylinder is clicking pretty loudly. I probed it with a scrwdriver and there seems to be more mechanical noise on it than the others on the dirvers side. Is that normal?