I was having problems with my car sputtering at times and the code p0193 kept popping up. My fuel pressure would go from 20 psi to 80psi at times. Well i cahnged my fuel pump thinking that was the problem but now my Fuel pressure goes from 35psi to almost 90psi at times but it drives fine. What caaould be the culprit. i too it to a mechanic last week before i changed the fuel pump and he said my pump was going bad but i put a new pump so now what. BTW this is on my 99 gt. HELP...again