lurch or jerk at 50

[tchbil]

need help guys.....99 2wd 5.7 tahoe 199000 miles....ran fine untill I replaced upper and lower intake gaskets...now runs great around town but out on hiway as you get to cruising speed of 50 mph or higher and just lift off throttle a bit the truck will lurch or jerk under 50 runs awesome...cam retard is correct at -.5 have replaced dist cap and rotor,tps,spark plugs,has no trans codes has o2 sensor code from my cat delete.Ran fine before this just leaked coolant.....HELP