Fuel pressure regulator is right in front of the intake manifold above the distributer, there should be a schrader valve, looks like a tire vavle, on the rail in that general area use a Fuel pressure guage to test it, it should be at 40psi, I am thinking it may ignition related i.e. the coil, wires, cap, rotor, plugs, dont run platinum, also check the tps voltage make sure it's not way off and throwin more fuel in then is needed, also have you changed the o2 sensor, take a little bit and address the basic trouble shooting above and let us know what it's still doing, if anything at all.
1988 Lincoln Mark VII
Paxton Novi 1000 6psi kit, 30lb injectors 73mm C&L, MAF converted A3M, gt-40's, Felpro headgaskets, 1.7 Cobra RR's, typhoon intake,1 5/8 shorty headers, off road x-pipe, and full mandrel catback, electric fan, 3.73's, TKO 500, pro 5.0 shifter
372.4hp / 394.6tq 5psi
Rest in Peace Joel R. Bender.
July 30, 1979 - March 26, 2006