engine swap. now engine wont rev past 2800rpm's.please help. Options

[97celicast]

Hello new to this site, just wish I was in better shape coming on here the first time...

I just got done having a 4afe put in place of my 7afe that threw a rod. I could not find a 7afe anywhere so I had to buy this one... having a problem, I can't figure out... car will not go over 2800 rpm's down the road. if It tries to, it will sputter and buck, until it gets right at 2800 rpms.

when idling in park it will rev higher sometimes before it catches itself and stumbles back down to 2800...
so I took it to toyota 100 bucks for a 1hr. diagnostic... said computer is reading normal, no codes. mech. said either spark, or fuel.. so far put on new plugs/wires/cap/rotor/condensor. fuel filter... no difference.

had the coil tested it was within specs. read just as good as a new one... so Im getting good spark...

the 4afe I put in, was pretty much a long block. all intake,exhaust,sensors, alt. and everything else came off of my car...

Im leaning towards fuel, I bought a fuel pressure gauge, cant figure out where to hook it up, only place I could hook it up was on the outlet return line off of the fp regulator.. and only getting 2-3lbs. when running, so I don't know if the fuel pressure is as strong going back to the tank as coming into the engine. is there anywhere else I can hook up the fp gauge?

and when I blew out the old fuel filter the fuel was blackish or dirty looking....then put on new filter.. when I start the car, I can't hear the fp kick on... no noise from back there what so ever...car starts up fine, idles smooth, revs fine until 2800rpm's... any ideas I would really appreciate it...thanks...Lonnie