S10 Starting Issues

I just bought a 94 s10 blazer 4dr with the 4.3 vortec motorin it. when i looked at the truck it would not turn on, dead battery the people that owned it told me that the trucks been sitting for a yr bc they put a new battery(cheap walmart one, TRASH) in it and somthing kept draining it. I had the same problem with my 89 2dr s10 blazer, non vortec 4.3 and the problem was the battery was just too small so i have the most powerful 75 group size battery. So I put a battery from my 89 and it turned over really good but would not start. I ten sprayed starter fluid down the TB and it turned right on. So I found out it was not getting fuel, so the relays got swaped and still nothing. So I dropped the tank, it looked like the rubber mount bushing thing melted to the sending unit, so I replace the pump and put some new gas and it turned over a few time and i gave it some starter fluid an it cranked right up. It ran really rough one of the wires was arching off on the exh. man. so i taped it up and drove it to the gas station to fill it up. after I filled it up it turned on pretty easy. so I drove it about 30- 45 min to get it home. the next day I want to my job (advance auto parts) and I bought AC Delco plugs, Accel(olny $5 more than stock for the custom fit ones, I have them on both my s10's) wires, GP Sorenson Cap and rotor button, a peurolator fuild filter, AC Delco oil filter and 5 quarts of 10w-40 castrol gtx oil. I change it all gapped the plugs, filled up the oil everthing was perfect. A few day went buy just driving it locally and the check engine light came on code 32 baromic somthing sensor(I think it ment map sensor)/ egr, and code 80 something, trans solenoid 2 or 3/ ecm. Next day I put a new map sensor on it and undid the neg on the battery just in case. nothing but the light went off. Next day light came back on and said the same thing so, I fought and got the egr valve off. It had a chunk of carbon keepin it from closing so i cleaned it out really good with some carb cleaner. them put it back on with a new gasket. and it was find for like a month then the light came back on. My dad was driving it when it came back on with was the day before yesterday, he said it runs like crap it spits and sputtered then cut off. today Im going to yank off the intake manifold and leave it in some purple power and clean it all up. and see what happens. does anybody have any advice to help me get this truck back on the road??? any advice would be greatly apricciated(sp)

Thanks