My hummer H3 has been acting weird for the past month. When I'm driving pressing the gas not flooring it just steady speed I feel the rpm's go up and down. Not a huge feeling but you can feel it! I went to a shop and they said to start by cleaning the fuel injector system, it was a 3 part cleaning service he said they did. Went to pick it up and seemed like it helped but nope it came back, it seems like its not as bad but I have only put on a few miles. There is no check engine light on, called onstar and nothing came up for them. Any one have any ideas or have had this problem??? When I come to a stop it does not do it, only when im driving. Last thing I want to do is just keep taking it back and play a guessing game and keep spending more and more money. I asked if it could be the spark plugs but the mechanic said that he didnt think it would be that since i had no check engine light on.
Thanks guys

 

Just a guess but try looking at your throttle body, if dirty pull of and clean with throttle body cleaner. When you remove flexible hose you should be able to see if it is clean or not also open throttle plate it is usually dirtier on back side

 

Agree. Chem tool is great for cleaning that dirty tb.
Just make sure to protect work area with rags.
Chris

 

Happening when the a/c is on? The a/c compressor cycling, will cause rpm fluctuation.
Also, Clean the MAF sensor. GL