It could be many, many possibilities.
1. If you have not done a tune up an a long time.
Perform tune up, new wires, new plugs, new fuel filter. Check vacuum hoses, check irmc.
Still have problem.
do upper and lower intake manifold cleaning and replace gaskets, injector nose seals, etc. also clean behind throttle body, remove from uppper intake and clean egr passeges, etc.
Bob
