I bought this 01 Maxima with a bad IACV valve that took out the ECM. I replaced the IACV Valve and ECM in it. Now it idles good. When Im driving if I give it lots of throttle it will hesitate and barely go but if I take it easy on the throttle it will drive smoothly. If I am trying to get up to speed on the high way or overtake someone on the highway it will hesitate and barely go. Does this sound like a fuel pump issue or MAF?

There's no SES light coming on.

 

Was at a local wrecker today, found a early 2000's Sentra with a similar looking (brand new)MAF. Grabbed it for $5, couldnt go wrong I thought. Put it in the Maxima and she goes like a bat out of hell now.

 

I had the same problem, I just used Maf cleaner and it was like a brand new car!