1999 GMC Jimmy has a miss

I changed the fuel pump, it ran rough, so I replaced the sensor with the original, no change, a mechanic sprayed around the manifold gasket looking for bubble, non found but he said this was the problem, he said he could hear a change in the engine when he sprayed the brake cleaner aroudn the gasket, I didnt hear anything, the truck ran perfectly before the fuel pump change, my way of thinking is somehting to do with the fuel pump?