How Do I fix my 1996 plymouth voyager se 3.0l V6?

I have a 1996 Plymouth Voyager 3.0L V6 we had a coolant leak someone suggested to check the pipes that come from the lower radiator hose to the water pump SO we had to take ever thing apart the plenum, the fuel rails, vacuume lines, the throttle body, air box just to find out the leak was the water pump, so thats fixed but now we cant get it to run right we checked injectors and took the plenum off a few times trying to see if we missed some thing but i dont see any thing . If you drive it like you stole it it drives fine but if you try to feather the gas or stay at a speed it runs like crap. I need help!