[spareparts]

cfelton, check voltage at the coil when hot, odds are the resistor wire is breaking down, back track(take the tape off teh harness and unwrap it) the purple wire back up the harness till you find a short piece of hard wire thats shrink wraped, cut the wire just past this so it eliminates the hard wire and replace with a new purple wire going to the coil, if that doesn't fix the problem, make sure your shift switch isn't sticking.
As far as the rpm's on a 3.7, we used to spin them 4600-4800 wot, cuise around 3400. Biggest problem you'l find if you twist them harder is they break rockers