Just recently I dropped a brand new 4.6L v8 into my 97 f150. The truck was sitting in the shop for 10 months with 3 quarters of a tank of gas. When I drive it, it has sucky acceleration and the exhaust pops every so often. Well last saturday I had about 1/8 of a tank left, so I went and filled it with premium. It still pops. I have a little over 3 quarters of a tank, so it should have pushed the old gas out. It has brand new sparks plugs and new wires. I don't know what the problem is. The spark plugs are down tight and the boots are pushed down as far as they will let me. The injectors weren't too bad. We put injector cleaner in it before running the truck after getting the engine in, and after I filled up on saturday. Any suggestions? I could really use help.