Car runs like crap! pleeease help

Im going nuts!!! my car (1990 5.7 tpi)has been running like crap and ive been trying to fix it for the past two weeks! two weeks ago i turned it on and it sounded ok but when i put it in drive(with my foot on the brake) it started idling back and forth between 500-1200rpms and when i let off the brake it wouldnt go faster than 5mph and you could hear knocking and backfiring. So i checked the timing then i checked the codes and got a code 13 so i replaced the oxygen sensor ,throttle position sensor, idle air control motor, and gave the throttle body a good cleaning! it still runs like crap! i could drive it around but as soon as i go over 3000rpms it starts knocking backfiring hesitating like crazy!(one thing i noticed is that the throttle blades dont open when i step on the gas pedal with the car in park. they are suppose to open right?) i dont know what the hell to do!! someone help!!:confused:

What mods have been done?

Check your spark plug wires and spark plugs. Make sure none of the wires melted to the manifolds (or headers).

tps ?
maybe youre throttle cable broke ?

MODS(right now):
-383/9:1 compression/L98heads(portedandpolished)1.94/1.64
-Stock TPI(22lbnjectors,plenum,runners,base,etc.)
-MSD 6A ignition,blaster2coil,timing control box,superconducter wires 8.5mm
-comp cams 480/487,206/212
-SLP 13/4 headers,magnaflow catback

MODS(starting next week):
-Accel/Lingenfelter Superram plenum&runners
-Edelbrock hi-flo base manifold
-Ford Motorsport 24lb injectors
-Accel A.F.P.R.
-SLP cam 495/502,218/224

Leave it alone till you get the injectors and other stuff on then get a custom EPROM. See sig or PM me for details on the EPROM.