My 1997 1500 suburban keeps jumping in and out of overdrive while on the interstate. It will run fine, then start jumping a bit(not rpms, but the car itself, like its stuttering, but its very slight), and then pop out of overdrive and that sends me up 300 rpm. If i pull over for five minutes everthings good for a bout 10 minutes then it jumps out of overdrive again. then it will go back into over drive intermittently. Any ideas whats causing this? transmission failure? all other gears doing great, just not overdrive.

 

how's second if you get on it? . . . put in 2 after 40 and gradually acelerate

 

That sounds like the lockup clutch, not 4th gear, as overdrive implies.

 

well i winded it out this morning, never went past second gear cause i let off. but nothing slipped. just in overdrive it can't decide what it wants to do. if it is the lock up clutch, is that an expensive fix?

 

You have to replace the converter if that is your problem. I don't know what activates it in your truck, you might want to repost this in the transmission section.

 

I would check your brake switch to see if it is mis-adjusted causing the converter to lock and unlock.

 

Sounds like you are getting a misfire initialy from what you described. I believe with OBD2 if you accumulate too many misfires it will automatically unlock the converter. What you are seeing is the converter unlocking which nets a 200-300 rpm increase. If it was actually going to 3rd it would be around 2500 rpms if not higher. On a stock truck you typically do not feel torque converter lockup either. Has it ever had a tune up? If it hasn't or its been a long time I would try that first. Plugs, wires, cap and rotor.