Hi everybody from France, and sorry by advance for my bad english, I hope that everyone will be able to understand me however. I own since two months a 96 5.7 Suburban with about 130000miles. Transmission has been rebuilt few years ago. My problem is that the car violently, and intermittently, jerks since/from about 55 mph, and beyond/over this speed, even at constant speed or when I m accelerating over 55mph. So, it is very difficult ( quite impossible indeed) to exceed 55 mph, because jerks are impressive. It doesnt make noise, I don t think that RPM vary/change when it jerks, it seems that the vehicule is violently stopped during 1/4 sec, as if someone push hardly on the brakes a very very short instant....no idea at all of such a trouble . Should it be a TC problem, locking/unlocking? Or fuel pump/fuel filter?? Injectors are new x8.. No trouble code. No brake light on.. Many many thanks for your ideas and help. Regards, Fred. France.

 

Welcome to the forum...
Have you tried shifting from Overdrive to 3 to see if it still does it?

 

Have the same issue I have tried this mine is a 96 sierra 5.7 only thing I have noticed that helps and working on testing my theory is just barely put left foot on the brake to engage the lights when I do this mine does not buck anymore and I slightly see the RPM go up about 200rpm but while I hold brake and drive it stops anyone here replaced brake switch as maybe it is faulty? Getting bad signals but working normally otherwise