I have a 99 trooper and have been told to add seafoam in the fuel tank and manifold line. I have replaced my egr valve hoping my check engine light would go out and it did not. Other work has been done on the manifold intake gasket/valve whatever, and the light is still on. I was told that using seafoam would clean out the line and possibly make the check engine light go off. When they hook my truck up to a computer, the only thing that comes up is the stuff that I have already had fixed.
All comments will be greatly appreciated.

Have you cleaned the EGR Port (it is a tube that connects to the EGR the exits right behind the throttle body butterfly.

Read up on the FAQ's on how to use sea foam.

Also, if you have codes post them here and we will try to help.