I have a 2007 Hummer H3. I have noticed recently that when coming to a stop, the RPM's drop to around 400 or so. You can feel it start to bog down almost like it is going to stall then picks back up to normal idle. My wife drives it alot and she called me today to tell me the check engine light came on so I had her stop at the dealer on her way to work to read the code and the guy at the dealership said it is showing a problem with the number 5 cylinder. Any idea what could be causing these problems or if they are even related? Also, I had it serviced a week ago or so and it was low on coolant by about half a gallon but no leaks were detected so not sure if that ties in as well. I couldn't have her leave it at the dealership today because she had to get to work so I'd like to hear any ideas what might be going on. Thanks in advance for any help.

 

Do a quick search for these problems... TONS of threads on your issues that will be helpful.

I do know that the rpm drop is from a dirty TB ( Throttle body ) unit and mass air sensor.. Takes 10-20min to clean and will help out. Make sure u get Mass Air ONLY cleaner as well as TB ONLY cleaner so it won't damage anything. Be careful to just spray the mass air sensor, not touching it/whipping it dry. TB is easily cleaned with old tooth brush and a few rags..

The coolent issue has been discussed here before.. I can't remember the "fix" for that, so just do a quick search. Good luck

 

Mine started doing the same thing I cleaned the TB and it was really dirty that fixed it.

 

Yea just went thru this wit gf's 06 h3.

Throttle body dirty... chemtool spray
MAF dirty... MAF sensor spray
Wipe out air intake tubes
Watch for proper alignment of bolts and tb.
No gasket needed unless the one on the h3 is damaged
Spark plugs replaced 41-103
Spark plug coil ( this is just for ref you can pick em up local and cheaper)
2007 - 2009 Hummer H3 Ignition Coil for L5 3.7L at 1AAuto.com
Chris