Revs under braking at low speed

[BG1988]

2011 tahoe just had it in for a tune up last week. Before it went it it was reading a misfire on cylinder 7. work that was done at my local garage was new plugs all round, new coil pack cylinder 7, cleaned the throttle body and a full mobil 1 oil and filter change plus new air filter.

truck runs great but is revving when im braking, as i was slowing down i shifted into neutral and the revs shot up to 2000/2500. Checked all hoses and didnt find anything loose as i thought it may be a vacuum leak.

Any suggestions as i ran the scanner over it and it all came back clear.


Thanks

MAF mine would randomly do this tell i replaced it

sometimes it would even FULL throttle while idling or HIGH idle at 2500-3k rpm random... check the G/S (MAF "g/s") and IAT

the IAT should be with in 2 degrees of the outside temp..

MAF is the most common problem of the GMT800/900 series

 

[Big English]

Thanks for the input everyone, was happening for a few days then another code came up saying cylinder 8 was mis firing. Had that in the shop and replaced the coil pack. All seems to be running good again. Weird that 7&8 went within 2 weeks of each other.