maf sensor
 

I installed a rebuilt maf today when i started the car it started out rough then it sorta leveled out but now it only idle at six thousand rpm when i rev up the engine it drops down past five thousand then back up to around six i have undone the ground to see if the computer will reset and going to leave it off til i get off work sat. any suggestions .and it surges when accelerating hard what's wrong

Vacuum leak or torn boot after the MAF is the most likely