1990 Tracker with stock engine, free flowing intake and exhaust. Occasionally will lose engine power. On a typical hill that I drive 65mph, will only pull at 45mph. Engine still runs smooth, just with less power. The problem is unpredictable. Timing is correct, new plugs, new fuel filter, gas purchased from same vendor for over a year, daily driver. Noticed my gas mileage dropped from the usual 20mph to 15 mph on the last two tank fills. Any ideas would be greatly appreciated.
