Yes, call Mark at his shop. He will help you out.
What I can tell you is that before I blew up my motor at 5,100 miles I had the FMU with the boost retard adjustment and my fuel used to spike at 80-90 at 9-10 lbs. of boost with stock injectors. That is bad. Also, mine is a 95. My car would fall flat at around 5,300. You are probably running out of fuel at 5,000. Your car probably has the Edlelbrock Performer heads if its an early 96 car like mine. They don't flow worth Sh#*. Also, our hacked Cobra intake would have been better left alone also. They did leave it alone in later cars. Your fuel pressure should rise all the way up with boost depending on what injectors you are running. The 97 update cars don't usually come with a regulator. What else do you have going on? Upgrades? I don't want to lose the look of my car but if you want your car to pull all the way up you should look into some AFR 185's and the Trick Flow R upper and lower intake and a new more agressive cam. The Saleen custom S351 grind cam is just a mellow Crane cam and is also worthless. There are two types of S351 owners. Those who have lots of miles, and by lots I mean 35-30K miles on them and they drive it like they are driving Miss Daisy. The other half are like me and bought this car to put my foot in it.
With a decent tune and powerpipe ( don't pully down and don't cog drive it )you can see 600 RWHP with our cars with that combo.
I'm still on my safe tune so all of the timing has been backed out of my tune and I have only been running a couple of pounds of boost until I break it in so I can't give you an accurate fuel pressure reading from a healthy car.
THE BEST THING YOU CAN DO for your car at this very moment is go get your car dyno tuned and GET RID OF ANY detonation. EVERY SINGLE S351 that came out of Saleen ( 94-99 ) even the 99 cars and yes I mean ALL of them have a ridiculous, totally worthless tune. They were so worried with the emissions problems they never got any of the tunes right even with the N/A cars. Sorry to tell you your bottom end IS NOT forged. Unless the previous owner already rebuilt your car you are driving a R-Code grenade. Also, if you have no FMU you may have the also worthless 97 upgrade. Well, near worthless without a good tune. Do you have a six speed?
I love my car and will never sell but there is a lot to learn about owning one of these cars. After you talk to Mark, give Joe a call at
http://www.chicanesport.com/
Joe worked at Saleen from 1988 until the mid to late 90's and knows almost everything you need to know about your car. He rebuilt my motor. He also was on the build team that built your car. Here's the bonus. He has a fellow named Mike working there now and he is a former S351 employee. He knows more about S351's than anyone on the planet. Hands down. Like I said the best thing anyone can do is go get your car tuned right after you buy it.
Your car will love you for it.