318 trouble!

we installed a new engine(long block) in my buddys truck.the thing idles ok but there is no throttle responce! it just go up to about 1500 rpms and tops out.it kind of acts like a car with a bad cat but i checked all that.there are no check engine lights and the scan tool says it ran in closed loop so the engine thinks its running fine.the only thing i could find is on start up the IAC opens more than it should and it sounds like a heel of a vac leak the map snrs also is reading 24 hg so what is causing the iac problem and why so much vac im sure they are all the same problem.i allready regrounded all the grounds on the engine and im not sure if there is low fuel pressure because there is no shrader to check.thank alot for your help!

oh yeah i bet this would help 97 1500 4x4

Something with the throttle position sensor maybe?

Are you trying to rev with the pedal or by hand?

both do u have to reflash the comp after new engine install are the old peramaters the problem????