GM-GMC: fuel pressure regulator, fuel pressure gauge, fuel pressure regulator

Question
96 gmc 5.7 liter engine, hard to start,once started it will not take the fuel, sitting still or on highway, on the highway you have to ease on the throttle then takes off. have to crank few times after sitting over night. after started it starts very good.

Answer
I would suspect you have a fuel pump issue.  The fuel may be draining back to the tank after sitting for a period of time or not delivering the correct pressure.  You will need to install a fuel pressure gauge and check your pressure to see if it is within specifications.  Should be in the 55-62 psi range.
hope this helps