I have a 1990 chevy silverado 2wd and it seems when it gets up to running temperature it seems to idle very low. The oil pressure gauge seems to drop and raise and sounds liek the engine is gonna stall. Does anybody have any ideas on how to fix this problem?? I have raised the idle which have seemd to help a little bit and replaced the cap and rotor last year. Any help would be greatly appreciated.

i would recommend a tune up if it has been a while...how about the air filter and fuel filter? is it carbed or fuel injected??

My 91 does the same thing. It has a new engine, o2 sensor, manifold temp sensor, egr, egr solenoid, new filters etc. Running out of ideas here.