check engine light stays on after starting car

have a 1999 malibu.. check engine light came on took to auto zone ..they showed a p1404 .. egr valve stuck in the closed position... took to garage mechanic ran on their machine and he said that the valve was working okay...he tested the valve with the car running and hooked up to his machine... he cleaned out the lines and cleared the code... light was out .. he test drove it for four or five miles ... i started to take the car home and the light came on and stayed on again... any ideas... i even took off the gas cap and then put back on after a few seconds no change... any help would be greatly appreciated...

Get it scanned again to see if you get the same code. If you do the EGR may need replacing. Cleaning of the EGR may have temporarily helped but now it is seized up again. The original mechanic that looked at it should be able to take it off and know if it's the same issue. Make sure the electrical connection is also properly plugged

engine light is for emissions
perhaps it is your catalist getting clogged
have you recently changed fuel brands or octane ?
mines did at 58,000 miles same symptom but extreme loss of power.
performance fine driving slow.
i believe if under 80,000 miles it's a warranty