I just purchased a 1984 Mustang Saleen clone which has been sitting in a garage for about 10 years. After pumping out the old fuel, installing a new fuel pump and filter and a new Vortech supercharger I got it running. It runs excellent while cruising, but it breaks up and misses under acceleration. The motor appears to be a stock 5.0 with headers and exhaust, so I ordered a new set of plugs as I thought that might be the problem. I pulled out the first plug to check it and it looks like the mixture is good - nice tan insulator...BUT when I compared the length of the thread end to the new plugs I bought it was much shorter. The plugs in the engine now are Bosch Platinum HR98PY, and the plugs I bought are Motorcraft AGSF32C. If the Motorcraft plugs are correct - it would seem that the shorter plugs are why the engine breaks up under acceleration. I’m hoping for some advice.