Need help badly!!

[95GTS]

Ahhh!!!! This is driving me and my buddies nuts! The car is an 89 GT, same car I've posted about on here such as for the adjustable fpr, and we can not get it to run right. The problem is we can't get the fuel pressure to adjust and it will not idle correctly.

The problem started out to be that the car would not idle correctly. It's wants to surge and then die. It starts out at about 1200 rpm then drops and surges a few seconds before it dies. Also, at about 1800-2000 rpms, it would buck like it wasn't getting fuel (consistently in every gear) as well as some through out the rest of the rpms. You could tell it wasn't running right when driving down the highway. All plugs, wires, distributor cap, rotor, and fuel filter have been replaced. TPS has been checked and set correctly. Timing is set at about 13-14 deg.

So we hook up a fuel pressure gauge. Hmmm...25 psi. Ok, we replace the fuel pump with a new 190 lph. Now the fuel pressure jumps to 55 psi and won't come down (car already has an adj. fpr). So we figure, bad regulator. BTW, car still idles the same as mentioned before. We put on a new Paxton adj. fpr last night. Still idles the same and the fuel pressure pegs (gauge goes to about 65 psi) and then drops to about 55 psi whenever rpms go down and pegs when rpms come up. Same as it has been doing. BTW, with the car shut off the gauge reads about 25-26 psi. Before the new fuel pump it read 0 psi with the car off. With the vaccum off or on it won't adjust the fuel pressure. So we've replaced the regulator when it wasn't even bad. The only positive thing about that was the Paxton matches his car and the other blue anodized looking parts, hehe.

Now what to do??? The TPS was set at the correct voltage. I believe it was around 0.98 but can't remember exactly cause another buddy did it. Could the IAC be part of the problem?? We have no clue where to go now except off a cliff with the car. How exactly do we check the MAF to make positively sure that it is calibrated for the 24 lb. injectors? We are pretty sure that it is but not 100% sure. He's only had this car a few months and the guy that he bought it from didn't say anything about it and we can't get ahold of him.

To refreshen, for those that don't know, the mods for this sucker here ya go:
GT40P heads, Cobra upper/lower, E303 cam, 1.7 rr's, 24 lb. injectors and MAF, 70mm TB, K&N w/cervini's ram air, Paxton adj. fpr, 190 lph fuel pump., 4.10s, 5-speed, BBK lca's.

Oh I just thought about this. This car used to be an automatic. Could that be the problem? Like with the computer? We've run a computer scan but nothing comes up. Just a thought.

We're really confused about the fuel pressure. We need help bad. What do you think is wrong?


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1996 Mustang GTS