After a tune-up on a '93 Chevy G20 van why would it have a hard time starting then when it does it spits sputters and runs rough?

crossed plug wires Like above only will explaine.. When you were doing the tune up you either turned the distributor or mixed up one of your wires unhook the coil wire and get a friend to turn the engine over in bursts you check the timing marks on the crank when they are both lined up you either have number one or number six pull the distributor cap off to see where the rotor is pointing at, it should be the number one spark plug wire. If it is not there is your mistake go from there and follow the firing order that should be marked on your intake manifold .1-8-4-3-6-5-7-2 Wayne