My newly purchased '92 K5 takes several turns before it starts, the engine seems to stumble upon acceleration AND when it shifts, and idles about 900rpms. I bought the K5 disabled and had to replace the tranny and transfer case. I mention this because it was disabled for several months and I figure that fact might help in the troubleshooting.

I've replaced plugs n wires, to no avail. I've also:

1) Made sure the vacuum is squared away(several things were disconnected)...all the hoses are connected according to diagram now and it has a strong, although not gauge measured vacuum pull. I have no vacuum gauge available. The problem persists.

2) Bypassed the egr solonoid by removing the line side and egr side vacuum hoses and coupling them together. This engages the egr and stalls the engine. Also, if you crank the engine with the egr vacuum line disconnected it runs regularly(still high), but then when you reconnect it while it's still running, it stalls the engine.

3) Removed the electrical connection from the map sensor, which stalls the engine.

The throttle-body spray seems excessive. The fuel mileage seems low.

Does this model K5 have any self-diagnostic capabilities? And this is off subject, but I'm also having trouble finding the oil pressure sending unit, but that's not as important as some sound diagnostic advice. Help me out!

 

My main problem to be turned out a stuck IAC valve. The truck had been setting up for a while and I guess the IAC just froze up. It ohmed out properly, it sounded like it was trying to move, but wouldn't.

When the IAC is working properly you can rev the engine and when you take your foot off the throttle it un-revs noticeably slower, it doesn't just free fall back to idle. If you don't have that noticeable wind down hesitation check the IAC.

WEHALLLLLLLLLLLLL!!!

 

if its a throttle body they are notorious for sucking the gasket causing idle and decel issues