[Pontiac5519]

I reassembled and painted this truck after it sat in my barn for approx 10 years. Just recently took it to town for gas and thought it was going to fold on the way. Had it floored and headed for a close driveway. Threw it in neutral and finally built RPM and it was fine after that. Left it sitting for 2 days and it wouldn't start, it would fire then it wouldn't.
Pulled it in the barn and pulled the top off the carb and blew it out. Changed distributor caps including HEI which is still on it and did no good. The plugs just look dark but clean and okay, the fuel filter is free flowing and I didn't get it started till I started moving plug wires around. They do need replaced and I wired tied them up temporarily. When it did start I couldn't build any RPM in any throttle position. After it warmed up I drove it all around in the snow and had a blast. Started it this morning and it started better than I can remember and the wife took it to work and turned around and came back because it was trying to die out again.
I am wondering if it has to warm up a long long time before it is okay. It also has ESC (Electronic Spark Control) I am wondering about the fuel pump or the ESC. I removed the EGR and made a block plate for it. I also wonder about head gasket due to milk in the valve cover to carb vent tube. Other than all that, I'm kinda at a loss.