94 GMC 1500 shifting problems

[Twisted Illusionz]

Been doing research on this particular problem for a few weeks. Can't seem to find an answer. Truck won't shift into 2nd. have to take the revs up to 3500 then let off the gas and it will shift straight from 1st into 3rd. Slowly give it gas after letting off and it will run through the rest just fine. All the gears are strong, no slipping just wont shift into 2nd. Any help would be greatly appreciated. by the way changed to a corvette servo and that wasn't it.