91 S10 Runs like crap!

OK , it has the 4.3, auto. I have replaced the plugs, wires, cap and rotor, PCV, O2 sensor, MAP sensor, (the last 3 due to the SES saying so!). Still it runs like crap and smokes, especially when cold.

I think it is electrical and I will tell you why. I drove it to Hollywood for a gig. I unloaded my gear and when got in it to move it, it clicked and smoke started coming out from under the hood. I popped the hood and the red wire going to the alternator was hot and melting the insulation! Whenever the key was in the start position it would glow, and not turn over. I went the next day and spent an hour and a half trying to figure it out. I looked under the engine and there is the wire that comes off the starter. I just tugged on it a little for shits and giggles and the damn thing started right up!!! That is when the crappy running started. Has anyone ever heard of that before? I mean the truck feels like it is missing.

Any ideas???

You need to check the wiring down there on starter real good.