Usually during interstate trips after passing or maintaining speed up long hills. The light will blink and sometimes it stays on for a while sometimes not. If it stays on, it goes out eventually.

After a major tune-up a few years ago, it didn't do it as often but still does once in a while.

 

Run to AutoZone / AdvanceAuto / Etc and have the codes read, as they do it for free. Once we have the codes we can figure out the repair.

 

does a march 2002 astro van have a egr valve. autozone sold me one said this will cure hesitation when axcelerating. not on intake manifold