i guess it just stalls when the rpm goes to 4 it kicks in to normal speed and rpm goes back down to2.But my check engine light is on
Does this bulletn from GM sound like what you have going on?
#PIC4252: Buck While Driving Stall SES Light Flash Door Locks Cycle CD Player Skip Clock Reset - keywords amp blown fuse ground idle inop inoperative intermittent L61 LE5 P0121 short STG surge trunk wire - (Oct 5, 2006)
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Owner complaining that the vehicle would buck while driving at times, may stall, ses light would flash, door locks cycle, cd player skip and reload, and clock reset to 12:00 It has been found that the Red/Black wire circuit #142 shorting on left rear inner quarter panel. It was not blowing the 50 amp maxi fuse right next to the battery in the trunk. This circuit feeds, hot all the time long term memory for ecm, tcm, bcm, radio, rcdlr. The wire is taped along with one other wire, the location is just to the rear of the subwoofer (must remove to access to remove trunk liner).
Note:: Your vehicle may or may NOT have a subwoofer, however the wiring is the same.
Remove damaged section of wire and repair, install insulation over edge of inner quarter panel, and install conduit..
#PIC3457A: SES Light On or Various Driveability Concerns - keywords backfire cold DTC G103 hesitate idle INT intermittent light low MIL rough stall start SES various warm - (Dec 7, 2005)
A customer might comment about a SES light on or Various driveability concerns intermittently.
The first thing to check is Ground G103 for it being loose, If it is tight then proceed with current diagnostics.
Note: This ground is located behind the left front head light assembly on the top of the frame rail.