ok here is the deal, my 86 k5 has a lugging problem. if im applying throttle more than half way the truck runs fine. but when im coasting and just holding the truck at a speed, it has random lugging actions, that almost feel like a misfire. and i know the first thought is misfire, or fuel. but ok im three months away from graduating wyotech, and i have been thru the automotive program so i kinda know what im doing. but anyway just to give you guys the run down to help narrow it down, i have check the entire ignition system and im getting proper spark everywhere. its carburated and i have check to make sure that there is no problem with fuel flow or if anything is clogged up and everything is ok. so then i went to the brakes to see if i was dragging. and my right rear was having problems not spinning freely so i cleaned everything up and disconnected the e-brake because it would not release. i test drove it and still no fix. my next area is the front right caliper because it froze up on me once and really warped the rotor, and my question is could that be doing it? and also i have a 4-speed manual and i was wondering could it be the tranny? i have been fighting this for 6 months and i need help. any ideas would be greatly appreciated.