Suburban :: 99 - Loss Of Power And Oil Pressure

I bought a 99 Suburban 4x4 with 205,000 miles for hunting, I recently took it to my property in the Texas Hill Country. The road to my property consists of dirt with large rocks, you are required to lock in 4 low and to the climb, on a very steep hill I reached about 3/4 of the way up when the suburban had no power, it idled but my foot was all the way down on the pedal and the tires would not turn or spin out, I backed down and tried going a little faster, same place it stopped moving and this time the oil pressure dropped and the check your gauges light came on, once again I backed it down. On a level surface it drives great but on a steep incline it develops this problem.