I have a 93 Ford explorer XLT, 5speed, 4x4, with 30x9.50r15 on it. I live in colorado and i often go to the mountains (11,990 FT). The drive up is killing me i cant seem to get my exploder to keep a constant speed without having to rap it out (im always in 3-4 gear between 3.5-4 thousand RPM)...