This truck fires off fine cold, but once warmed up, it turns a bit harder. It slows down enough that it is difficult to fire, but once it does, runs fine. I haven't checked the cables out yet, but since it has been a long running issue, thought it may be heat soaking the starter. I put a different but used starter on it and seemed to be better, but now it is back. It is still the old direct drive starter as well. Thoughts?