GM-GMC: 1994 350 suburban loss of power, shaft bearing, distributor shaft

Question
it seems the truck loses more power the hotter it gets... it also shakes pretty bad in first and second gear as the power deteriorates.  i have checked the plugs and distributor, and have changed a bad tps.  i may have a bad fuel pump (my alternator gauge drops when the engine gets sluggish) or a blocked cat... or even a bad alternator.

do you have any ideas off the cuff?

Answer
Well to be quite honest, I have seen a dozen different things cause what you are describing.  It could be a plugged exhaust/convertor, it could be a siezed distributor shaft bearing and so on.  The best advice I could give would be to start with the simple stuff. ie..timing, fuel pressure etc and try to work your way through in a logical sequence.
Hope this helps a little bit.