I bought a 89 as a project truck the fuel pump and headgaskets were shot. I was able to get the pump going with some lube and replaced the gaskets. The truck ran decent, it was always hard to start and their was hesitation when accelerating. Eventually the pump died and I figured all the running issues were related to the pump.
I replaced with a new unit and it doesn't have any hesitation now but the truck wont start in the cold. You have to start it off quick start then it runs rough till it gets warm.
Where should I start looking?