1997 GMC Jimmy hard time starting

Gave a complete tuneup, wires,   plugs, cap. Rotor. Fuel filter. Service engine soon light came on and was check it read, running rich (bank 2) and I replaced #6cylinder fuel injector and the engine runs better. But in the morning the truck starts and runs fine. After a while driving it and the engine is heated up I will shut it off. Then go into a store for a few minutes and come back out and it takes several cranks before it starts when its warm. Any idea whats the problem? Thanks mike.