I have a 1999 4-D Blazer 4x4 with 4.3 Vortex. I have had nothing but problems with this truck. I have 102,000 miles on the Blazer and on my way to work today I had a clunking noise somewhere in the right front of the vehicle while in 2 wheel drive. As I drove it got worse, it didn't matter if my foot was on or off the gas. Then along with the clunk the truck started to buck and the service engine light came on. I have replaced U-Joints recently and I have put new wheel bearings on both front. I have also been having problems with my 4x4, I will normally get the same clunk noise when I have the 4x4 engaged and the 4x4 works only when it wants to, I think that is a vaccume problem, but I am not sure if the two may be related. This is the first time the service eninge light has come on.

Autozone can check the codes for you.

have the codes checked and tell us what they are and we will go from there