I have a 96 cherokee with 4.0L, AW4 transmission and 102,000 miles. After driving on the highway for an hour going 70 mph the engine seems to jump for 2200 rpm to 2600 or even 3000 rpm. There is a loss of power at these high rpm. I have checked transmission fluid and it looks fine. Gas mileage is also low around 13-15 mpg. Another problem maybe related or not is the four wheel drive light does not go on. Checked fuses and all look fine. Any ideas on where to look.