well for the 4th gear mod look here.
www.gcrosset.com/zipzaps. i love my truck with the 4th gear mod plenty of power now, belive me it's worth it. i am also looking for wheel wieghts, the only thing i've tried to put in those slots was clay but it wasn't heavy enough, are you sure that tin foil will do the job?
ok with your acriculated mt hold the rear end with the whole thing in the air and give it gas and tell me if the front trys to move, this will prove my theory.