Chevrolet Repair: Stalling and hesitation, 1990 chevy lumina, e mail address

Question
I have a 1990 chevy lumina 3.1 it's stalling out when u push the gas and attempt to pull out. It will also hesitate at times but it's pretty much to the point to where it just stalls out completely. I;ve changed the egr senser, air in-take senser, throttle poistion senser, and today I put on a new fuel filter. After insatlling the fuel filter it ran perfect no hesitation no stalling. Until my idiot of a ex boyfriend changed the spark plugs. Now it stalls out constantly. More then before actually. I don't know if he crossed wires or if he has a plug in wrong or something. I don't know where to find out if the wires are crossed.  

Answer
If he had crossed the wires it would pop and backfire if it even started. I will need to do some homework but I believe the problem is in the fuel pressure or a loose wire dealing with the fuel system. E-mail me at zimmer_jrz71@yahoo.com so I have your e-mail address and we can communicate back and forth. Without being there to look at it we will need to play e-mail tag for awhile to figure out the problem. Sorry for the timely inconvenience.