2000 Jeep Wrangler 4.0L I6, Auto.
I purchased a jeep for a steal about a month ago, and the previous owner had upgraded a lot of things on this jeep. Two of the many upgrades are 33" Tires, and a 4" lift. I have been getting terrible gas mileage, and have a hard time getting over 70MPH, god forbid I am on any incline. So, I slid under and took a gander at the gear ratio it had and it is 3.07. What gear ratio should I have with my Jeep, and these upgrades? Would the gear ratio be causing the very low MPG's, and trouble gaining speed?
Also, every so often my oil gauge will drop almost instantly from 80 to 0, and then slowly start going up, and then drop back to 0 again. After a little bit it will make it's way back to a steady 80. Any ideas?
Also, also, will I have any problems with this setup having the stock yoke and drive shaft?
My Jeep (Sorry for the bad pictures, will post better ones later.):