New Engine need help!!!

hi all just recently got a new engine (second hand) into my 94 wrx but now it will only rev to about 4000rpm before it dumps boost,
what should scoobys rev 2 and how can i fix this?
also, it cuts out sometimes under heavy breaking and often drops below idle level causing steering to be heavy.

would greatly appreciate any help or advice! thanks

Could be your MAF sensor.....

Alan.

Was there something about a wire at the back of the speedo :S Get it pluged in at a garage