same thing happened to my 96 aw4, it was a solenoid. the 1-2 solenoid. Real easy fix, worst part is dropping the pan and there all right there, heald on by one bolt. Should be a dealer only item at around 250. If you don't have the money go to pnp and grab a few.
Their pocket sized ;-) Flushed it lately? I'm having manifold-to head vacume leak issues. new motor is running crappy. I don't think i lined up my ho head to my renix manifolds right. Dropped it off at gear shop today to get re-geared. Getting it back hopefully tomorrow so i can address the shit-stink leak. I hate unbolting these manifolds. AMC should have put exhaust on other side.