Truck does not start well..?

[static22]

Originally Posted by squint

No it never did this with the old engine.. It fired right up. no gas needed..
and no it does not usually fire.. it just turns over and eventually fires.

It sounds like it could be electrical. Maybe when you were putting all the componets back on and wiring them back up you didn't get a wire crimped well or one is not making good contact until the engine warms up and creates a better contact by causing the metal or wire to swell slightly. Has it done this from the first time you started the new motor? It may take a little while to find but just start ruling out things one at a time. How "new" is the motor?