Thanks Ed. I'll look into the things you listed. I ran a brand new cat with a plug in the O2 sensor whole for a while since I couldn't get the old sensor out of the stock manifold. The cat very well could be clogged from running rich. The EGR tube got looked at when I had it apart, but I'll give it a cleaning anyway.

Update: The motor is apart and getting re-bored to .040 over. I guess it's a good thing I didn't go all the way the first time. I took the pistons to be examined and was told that the damage looked like it was caused by "severe detonation" due to a "lean" condition. The pistons in #1 and 2 cylinders were HAMMERED. The rings were seized in the grooves from heat, and it looked like they tried to sieze. Luckily, the crank and rods look ok. The pistons got hot enough to turn the wrist pins blue.

I think I'll try to have the injectors checked (or put new ones in if I can't find anyone with bench tester) and change the EGR valve and backpressure transducer. I really can't afford to burn up another motor (I couldn't afford this one). Any other advice? The truck has to be running and broken in before my grandparents take it to Oklahoma in mid-December, and I still have to get a cruise control system set up for them.

Thanks for all the help!

BTW, please keep in mind that this is a '94 2.6 from AirAmigo's truck with '90 running gear and accessories.