I am working on a 86 22r motor. I have switched it from a donor truck, and replaced all seals and gaskets when motor was out. In the old truck it would not idle. In the next truck, I have the same problem. So far, I have switched carburetors, checked and rechecked egr valve, switched egr valve, new head and intake gaskets. It has a vacum leak, but I cannot pinpoint it. The problem has followed the engine. I have removed all the hoses from the maniflod with no change. I have sprayed carb cleaner all around the manifold with no change.Is there a possibility of having a cracked maniflod, or cylinder head?
Thanks for any help! This is starting to give me grey hair, and I have enough already!!
Rod

 

Are unused vacuum ports plugged on the carburetor? From what I've been told, the carburetors differed based on transmission styles, 4x4 vs 2wd, and federal vs California smog.

The best thing to do is acquire the FSM which has schematic of all the different hose routings per truck... vacuum, EGR, etc. There are also two units I am aware of that open/close off vacuum ports based on heat. I'd make sure these aren't cracked as they are made from plastic. They screw into the intake manifold like bolts, but protrude out and form two vacuum ports. There are two of these on the front of the intake manifold: one on top near the t-stat housing and one on the side.

Actually, now that I thnk about it, did you replace the PCV valve? (positive crankcase ventilation)

 

Check the compression of the vacuum advance, if there's no compression or low it can cause the carb issues.

 

I finally found the problem. Dirty carburetor. I had cleaned and kitted the carburetor earlier and had ruled it out as the problem. After hearing of others having the same conditions and being the carb, I did a more thorough cleaning. I removed the idle mixture screw, the anti-diesel solenoid(?), sprayed lots of carb cleaner in the ports and blew with compressed air. I also sprayed carb cleaner in the bowl vent while the engine was running until it almost killed the engine, and then left to eat dinner. I came bacl about an hour later, started it up and it just kind of magically started straightening up, and ran very smooth.
I hope this will save someone else the grief and extra work I have had the last few days.
Rod