My 2002 suburban has been shutting off going down the highway. Pull over on the shoulder and wait 1 or 2 minutes and it will restart with no apparent problems. If you try to immediately restart the engine, it will not start but is very rough sounding. Seems to happen after about 50 miles on hot days.

Perform tests in the link below:

https://www.askmehelpdesk.com/cars-t...ml#post2123675

Check/replace the Crankshaft Position Sensor and coils. Ensure that the platinum spark plugs (ACDelco only) have been replaced in the last 50,000 miles.

To add some background, about three weeks ago we had the oxygen sensor, Crankshaft Position Sensor, and a partially clogged fuel filter replaced because of similar episodes (but more frequent). My wife drives about 15 miles to work each morning with no problems. Will have to have the coils checked out. Thanks TGM.

Have any codes been thrown?

The service engine light had been on for a little while. The mechanic said there were codes for the CKP and Oxygen sensor. The service engine light has not come back on and I have not had it checked since he worked on in it.

You might want to check for any "soft" codes--it might tip you off on what's going on. Did the mechanic install ACDelco components?

Txgreasemonkey is always great with his responses. Coils and checking of history codes would make sense to do. Remember that history codes are eventually cleared.