LBZ MAF Bounce

Had a customer complain of a slight surge at certain times. Sure enough we drove the truck and I logged it and there was a slight surge where desired rail pressure dropped etc... so looking into what could cause this I noticed(wasn't hard to miss) the MAF was bouncing throughout the drive...at idle it was fine and stable, but under load it would bounce to 40 and back to 5 lb/min and the back up...it did this constantly under ANY throttle. The customer has an S&B air intake and I did a quick check for leaks. Is it possible the MAF sensor needs to be cleaned or replaced or is there some quirk I'm missing. This was a DSP5 tune as well running 52606128 OS. The truck ran fine for 6 months, so I was certain it wasn't my tuning that just now caused this...as I have tuned many and this one is a first...

The air intake plumbing/tube/lid/airbox is causing this, install the stock plumbing/tube/lid/airbox and see the MAF bounce minimizes

( I see this on gasoline vehicles quite often )

Is it pushing open the egr seen it happen at high drive pressure.

As stated above, when the EGR opens, the MAF will reduce logically. I don't think 40 to 5 is expected, so I would investigate EGR correlation, before replacing the MAF

I should have mentioned that the egr is blocked and disabled.