1991 mighty max, 5 speed manual ... when going up a hill, motor seems to race as if clutch is slipping, only symptom, no noise, no smell. once truck has been run, does not do this .... truck has 94,000 miles on it. Othersise is ok ... just noticed this problem in the last week or so ... the clutch pedal is 1/2 inch higher than the brake pedal.

If it has a cable for clutch you need to adjust it. if its hydralic then the master cylinder may be not bleeding off properly when cold or slave sticks when cold. you need to measure pedal free play that is how far pedal goes down before resistance is felt there needs to be 1/2 to 1 inch or so free play to make sure that the release bearing isnt riding on the pressure plate [would be the same as riding the clutch] the 1/2 inch higher than brake pedal probem can be adjusted on the pedal stop but shouldnt be the problem. of course the clutch could be just plain worn out to.