Jeb1865

First time poster, long time lurker (and newbie), so please bear with me. I have searched, but I have not been able to find quite what I am looking for so I am taking the risk of posting and incurring the wrath, haha.

I just bought a 1991 Pickup 3.0 DLX manual standard cab 4x4. I bought it for $1800, and it has 218k miles on it. Let's face it, it's an 1800 truck, but it doesn't have any rust, and the lipstick on the pig isn't too bad. It has a rough idle. It's like it has a cam in it, and it just burples as it idles. The guy I bought it from is a boat mechanic and had bought a PCV valve for it and said that was the problem, but from what I hear, that's a giant pain in the ass. I took it to a master mechanic friend of mine, but he's an Audi and Porsche tech, so he kept saying the engine is in the wrong location. He also said that I needed to forget about the PCV valve right now and that I should replace both intake boots and replace all of the vacuum hoses. Once that is done, then we can really diag any other issues.

I have replaced the intake boots with a cold air intake because it was actually cheaper and easier to find, but tackling the vacuum hoses seems like a tedious project, and none of them are visibly decayed. Has anyone run into this same problem? It cruises ok, but it's not the most responsive. I haven't really driven it after the intake, because I also replaced the alternator, and for the life of me cannot figure out how to tighten that belt, so it's squealing like crazy! (But that's another topic).

I am just a little lost right now. Thanks for the help.

thook

well, spray some starting fluid on the vacuum hoses. if they leak, the engine will rev a bit.

there's a number of reasons why it could have a rough idle. could be electronic in nature or purely mechanical. does it seem better or worse at all during the warm up cycle or after?

Jeb1865

I haven't been driving it long enough to get it too hot, because I don't want to get stranded quite yet. But for what little I have driven it, it cruises ok, but regardless of temp or length of driving, the idle problem is always the same. At stops, I just give it some gas to keep it running while I wait for the light to turn green or whatever. I feel like if I could fix the idle, I could easily take it on a road trip the next day. It just sounds like it's going to stall out as soon as I let off the gas.

thook

spray around the hoses and any intake manifold gaskets/connections are made. otherwise, test the throttle sensor. could have a worn contact at the idle position