Recently bought a 07 silverado 1500 classic 4x4 and just love this truck it has the 4.3 engine and now I am getting a misfire in cylinder 4 . also just had lifters replaced before all this began the mechanic cant seem to find the problem but loves to replace things and get my money . plugs , cables , distributor cap and rotor were replaced and coil pack . I get a check engine light on steady and after about 2 or 3 miles of a steady cruising speed it will start bogging down or slit hesitation and when I hit the gas it starts to sputter and then it eventually clears and speed starts going up fast please help

 

Possibly an injector problem. Try one of the better injector cleaners and see if that helps before spending any more big money on replacing more parts.