Check u joints, then check rear pinion flange make sure your pinion nut hasn't backed off. If it's ext cab make sire your center bearing isn't bad. Does it act like it could possibly be a fuel supply problem? That could explain whey you'd be surging under load.
Think you might be correct on the fuel supply issue. After a lot of testing I think i have it narrowed down to either a faulty fuel injector or wiring issue leading up to the injector on the 1st cylinder. The injector works at times and does not work other times. Not sure if it is the injector or the wiring its very hard to diagnose because it does not act up all the time. So when it starts acting up I'm trying to test everything I can think of before it stops acting up. Previous owner cut damn near every wire coming off the motor then ass connected them all back together. All injector wires were cut I thought I had everything soldered back together correctly but I might have missed something.
