I have a 95 Power stroke 4x4 5 speed. When the truck is idling it runs pretty good, but when you drive it after so long, or come up to a corner it acts like it is missing and loses power so it barley wants to pull itself. Do you have any idea why,any suggestions would be very helpful. Thanks

Have a scan done to see if there are any codes stored in the computer. Sometimes codes will be saved without the check engine/service engine light staying on.

This sounds like a EGR Valve problem. Remove the EGR valve and check that it not blocked / clogged with carbon. If it is give it a good clean, and check that the piston moves freely. Replace o-rings and base seal if required, u can get these from a Hydraulic store, ensure you get the correct type, normal o-rings will burn. Once clean reinstall and test drive. It may also pay to give the intake manifold a good clean, using a wire brush type tool that you can get down inside manifold. Plug EGR in, fit EGR valve but do not bolt down have someone start engine, will take some time, once running remove EGR valve anf run engine at high RPM for 2-3 minutes to blow carbon out. Hope this helps.