my 93 laredo is having idle problems sometimes it will drop idol and act like it's going to kill the truck.... and other times it will search up almost 1000 rpm. I have replace the idler air control valve and the throttle position sensor and a tune up with all the wires rotor cap... and im down to thinking it might be the crankcase sensor or even maybe an o2 sensor.....but don't wanna just keep tryin stuff i actually want the source...

 

Google "5.2 plenium plate gasket failure".