92 blazer has problems starting

i have a 92 s10 blazer with the 4.3 liter tbi engine and when i start it after it's been sitting for about 2 hours, it acts like its going to die for up to five minutes. While it's having its little fit, the check engine light comes on so i took it to auto zone and they said that it had a code for the map sensor. I changed the map sensor but the problem persisted. Once it gets warmed up it runs fine and the check engine light goes off. I have no idea what is wrong with it but i'm getting to the point that i just want to junk it. Please help.

Return to Autozone and get the codes read again and give us the actual code number.