I have a 2002 ford lightning that I just bought. The truck feels like it's falling on its face when idling or with giving it gas. What could that be? I've already changed spark plugs, new MSD coils and cleaned the IAC.

 

Must ask the obvious question first... Is your check engine light on? If so, what codes are stored in there? Seems odd that it would be running like that without the PCM reporting an issue.

 

I'd put the factory coils back in, -MSD COP's are Chinese knockoffs. Sounds like either your EGR valve is hanging open or your cats are plugging up.