1992 1500 Loss of Power Question

Heh,
After noticeing a loss of power going up steep inclines I gave the Chevy Silverado 1500 a major tune-up(caps, rotors, wires, plugs etc) and while it improved...it still has issues. Today going up the pass anything over 2500 rpms was a no go! It bogged and coughed and generally acted broken. Below that rpm it was relatively normal besides the raise in engine temp and that always welcome. "SERVICE ENGINE SOON" 150,000 miles, never a poor moment until today. Any ideas...like I said at lower rpms it seems ok. Thanks.

You need to pull the codes and see if you have a bad sensor.

Would a faulty sensor have anything to do with the loss of power or just the "Check Engine" notification?

It could be a number of things, weak fuel pump, bad fuel filter, misfires, bad catalytic convertor or a sensor that is feeding bad info to the computer. When even the oxygen sensor fails the computer will go into "limp" mode which will dramatically affect fuel mileage and power. It is just a failsafe mode for the engine to run with until it can be fixed. That's why you need to pull the codes and see what is going on. An OBD1 scanner is very cheap. Autozone even has the paperclip like tool that crosses the pins on the scan tool connector for you to get them. You will need a repair manual to cross reference them.