I've got a 2003 monte carlo ss, and recently has had a couple of weird issues. Last week i was driving at about 30 mph and the rpms were going haywire (1200-1500 rpms) along with a slight chugging sensation. Also my friend has a 00 monte ss and when were going 40 mph his rpms are at about 1300... when i go 40 mph in mine its at almost 2000? Does this sound like a bad torque convertor? or a bad overdrive sensor? its using more gas because of this high rmp, and chugging... I did have the plugs and wires changed at 100,000 miles

 

You may want to start by cleaning the MAF sensor element. It's really simple to do and it'll only cost you the MAF cleaner can and, if you don't have any, a 20 torx, I think, bit.

 

also i have noticed anytime i drive about 40-45 mph the rpms are almost at 2000? soon as i got about 46 it shifts into 4th gear or overdrive. what is causing this?