Having problems with your 1991 Mercury Grand Marquis ?
Engine idiles high and stalls when stoped every now and then
Sounds like a sticking EGR valve or partially open, try removing vacumm hose at valve and plug vacumm line, if no results remove valve and make a gasket of a soda can to match outter edge but no center holes install if fixes you need a new EGR valve
Repair Help & Product Troubleshooting for 1991 Mercury Grand Marquis
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