We have two similar trucks, so fortunately we can swap out parts to identify/eliminate causes. The 22R in our '92 is surging like crazy at around 3k. Can't get it to rev up any higher than that, just drops back down as soon as it hits that point.

We've replaced the plugs and coil, swapped in the AFM box from our good truck, just got done swapping in the throttle body in from our other truck, and it's still (*&^ing surging.

What could it be?