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Ron, ASE Certified Technician
Category: Mercury
Satisfied Customers: 35843
Experience:  ASE Certs and Ford Certs
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1990 mercury sable idol's okay when starts up, drive down

Customer Question

1990 mercury sable idol's okay when starts up, drive down the road for about 10 min. come to a stop engine idol's at about 2000 rpm. Replaced idol control valve, egr valve, old brake booster was leaking, checked vac. lines, gave engine a tune up, plugs and wires, filters, when idling at 2000 rpm's in park, turn key off restart idol's ok, go down the road and starts idling high again. When idling normal in park, pump brakes hard and the idol creeps up slowly. Any suggestions will help me with this problem.
Thank you, Mark
Submitted: 1 year ago.
Category: Mercury
Expert:  Ron replied 1 year ago.

Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

One very common cause for the type of high idle you are having can be caused by a failing Throttle potion sensor and if you are sure the new IAC is not defective I would suspect your TP is bad. You can check it with the enclosed test steps in the link below. Copy and paste your link to your browser to open the link.