I have an 89 xj sport and have just recently replaced the head gasket and got a valve job. I also have performed a complete tuneup and service including fuel filter. I had a rough idle problem to start with before the head gasket was replaced and now I’m having a problem while driving. When accelerating it starts at low end fine and when the throttle is half open starts to hesitate and skip but when I put it to the floor it clears out and runs seamingly well. I have put a new map sensor, iac valve, cleaned throttle body and put all new plugs ,wires, rotor button ,cap , fuel filter and air filter. Even added Lucas to the oil and gas and still have the same problem. Also all the vacuum lines and pcv valve have been cleaned or replaced. Any ideas?