94 V6 3.1 Idle

I have been having problems for a while with my cav with it stalling after I try to accelerate from a stop, and more recently its response to my accelerating is delayed (I put my foot on the pedal and it drops rpms, then accelerates). I have replaced the TPS, put injector cleaner in, and replaced the fuel filter. I can't decide if it's the fuel pump, EGR valve, or anything else. The throttle body has been cleaned out too. How would I test the EGR valve on my car though? It's not a conventional one and would cost me a hefty $220. My bets are on the fuel pump, though do these things go out gradually or suddenly? My dad was out messing with it last night, and I don't know what he did but now it won't start either. Thanks dad.