92 Suburban

You could have one or two problems with the car. I'am assuming that the car ran ok before the tune up. First thing I can think of is you put the wires back on the wrong way and now the firing order is off. Also check that the wires are on tight and not grounding out. You can check this with the car running in the dark and look for electrical arcs. The other thing I can think of is the plugs were not gapped properly and need to be regapped.