new and need some info...

[zachnaar91s13]

ok so i bought this 1991 240 ka24 twin cam from a buddy and he blew the motor so he got it rebuilt but...the ppl that rebuilt it were not nissan guys so they just slaped it together so it really could be anything but it just doesnt pull after like 3500 his old motor pulled to 7000 and now it just doesnt pull i changed my sp wires and got my timing set ata shop,took it to a few other shops and they couldnt figure it out SO any advice?

[S13 240SX]

sounds pretty fishy.

check to see if mass air flow is good or even plugged in,

check all wiring

or try to dissconnect battery and then get in and punch the break pedal for a few seconds, or hold the break pedal down for 30 seconds. this should re-set the ECU and the ECU could be stuck in "limp-mode"