I have a 99 Suburban with a 5.7 that I just recently had to change the heads and head gasket, now after the work was done I have a small misfire, plus the truck jerks at cruising speeds with a loud clack sound! What could be the problem? And thx in advance!

 

I know this sounds silly and dumb, but is your spare tire tight under the truck?!

I made a big deal once about this and it turned out that the tire got loose...

 

Actually, my spare is in the cargo area not under the truck!

 

That jerk at highway speeds can also be caused by the speed sensitive steering sensor...