Overdrive

I have a 94 ext cab with 87k miles on it. Trans has been serviced at all recommended intervals. The other day while driving on the interstate in overdrive. I felt a little jerk like an engine miss, then a little later I felt it again and noticed the speed droping off and then it shifted to third gear. It shifts back to overdrive but it doesn't seem to go, kind of acts like it is slipping. I thought in overdive the torque converter just locked up. Is this a torque converter problem or an electrical control problem or a transmission problem? I don't want to change the tranny if it is just the torque corverter or something else. Thanks in advance for any info.

You may try cleaning out your EGR, mine had a problem kind of like you were describing. As for tranny problems, check these out http://www.thesurecure.com/parts/parts/SC-4L60-E.htm and http://www.transmissioncenter.net/extreme_duty_parts.htm -Chris

Thanks, Checked and cleaned the EGR no change. Found on road test that if I shift back to drive with speed steady at 70 mph there is no difference, but at 70 if I remove my foot from the gas for about 10 seconds and manualy shift back to drive you can feel a down shift. My question is: is there a fourth gear or does the torque converter just lock up in Overdrive? I think it is getting the signal to lock in overdrive but it isn't pulling in overdrive so it shifs back to drive, with my foot off of the gas it is in overdrive since it isn't pulling and you can feel the down shift to drive. I think overdrive is gone so is it a new tranny or just a torque converter?
Thanks

Computer reprogramming update? Check with the dealer on that one. Fourth gear is OD, you do not have another gear. If your torque converter was bad, then you would have problems from first gear. You might have a bad lock-up solednoid which can be replaced by dropping the pan. check out www.atsg.biz where you can buy a tranny manual for your 4L60-E tranny. It will tell you more than you need to know about your problems. Cost is about $25 -Chris

Thanks Chris,

Further troubleshooting: Seems it is not shifting to 2nd gear either. Now thinking it may be the A solenoid, which I understand is the 1st to 2nd shift and the 3rd to 4th shift solenoid.
Dave

Thanks for the help and the links. It got me going in the right direction. I replaced the A shift solenoid and changed the filter and oil and it is working Great.
Thanks again for the help!!!