Just for show and no go
 

This sucks! I can't push my throttle past 1/4 or my stang sounds like I drove it into a pool. I can't even race the honda's over here in Miami and I have a 12 second car. What I noticed was that my fuel pressure gauge pulses between 38 & 44 psi while I'm idling. It never did this before. If I adjust the fuel pressure in any direction the pulsing will stop temporarily but will return to pulsing once I drive the car.
I would suspect a head gasket leak but I don't have any unusual water loss. You never know. I always run on the rich side and it smells like I do also. I bought a new TPS and I cleaned my EGR with short lived results. Please Please Please, if you find out what let me know. Thanks

Just me's hoopty trash compactor.
91'lx, 302 block, crank pulley, no smog, short belt, Wolverine 1087 cam, 15 deg timing, TFS TW heads, motorsport 1.6 3/8 stud RR, ARP studs, TFS chrome hardened push rods, 24lb inj, BBK 255lph fuel pump, Areomotive billet adj FPR, Performer RPM intake(ported to 75mm), 1" spacer, Motorsport polished tall valve covers(love em), Pro-M 77, Acufab 75mm TB, Ford idle air bypass valve, K&N conical, MSD 6AL and coil, 9mm MS cables, NGK bkr5e 11 plugs@55, motorsport 3 core radiator,160 thermostat, Hurst short throw, motorsport 410 gears, aluminum drive shaft,Kenny brown Subs, Mac 1 3/4"Long tubes, custom 3"off road xpipe, 2 chamber Flow Masters, 3 1/2" tailpipes HAL tubular K-member, KYB struts and shocks, Eibach springs, Steeda 2.5" Cowl, Steeda rear wing, black Dupont centari acrylic enamel paint.

past quarter throttle, then it falls on its face huh? i had the same prob. with all 3 of my mustangs. and 2 of my buddies. MASS AIR SENSOR. for some reason they like to go bad. its either that or your tps, but you said you already replaced that. it is a possibility that it is something else though. like a faulty fuel pressure regulator, or pump. but if you have an extra mass air laying around try that first.

Ahhhh buddies falling on their faces pissed drunk. I have some of those. LOL. Anywho, I tried my stock mass air and the problem goes away temporarily. I even tried a different computer. I had a similar problem years ago and it was a disconnected vaccum hose.
Hmmmmm. Anything else I should look for? I'm gathering all the info I can before I work on it.

the only other thing i think it could be is the fuel pressure regulator. look at the post ODD. its the same thing as you.

Thanks. I checked it out. The only reason I started another thread
is because the ODD thread was so long and I thought no one would see it. I was wrong lol. Thanks again.