is there a way to test a MAF Sensor on a ML430. It seems to run better with it disconnected.

 

Not really.
What codes have been set?
What has led you to the MAF.

If sufficient pointers exist it is likely the MAF. Your observation is quite normal when the MAF is bad.

 

When I hit the throttle, it stumbles pretty bad, can't hardly rev it up. fuel pres is good. I unplugged the MAF sensor and I could get it to accelerate good. I have no codes on my scanner, but the instrument cluster show 9300 when you start it. It shows up on the mileage screen. Thanks for your response.