Misfire. crappy gas mileage.

97cobraforever

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Jul 5, 2015
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East Bay, CA
Hey guys.
Im needing some advice.
i have a 1997 Cobra.
and I'm having some issues.
im getting Okay Gas mileage but usually it's gone to shit on short trips around town which I don't know why. It was the same on my 03 V6 and my brothers 97 GT. And I'm having misfiring issues. In the mornings or first start ups for the day. It's completely fine, or starting up an hour later after being turned off the car is fine.
but sometimes after starting up, I'll crank it and it will start to rev at 800 RPM's and stay there for a second, then move up to 1,000 RPM's./normal
i haven't checked the spark plugs, although I know the previous previous owner had the spark plugs changed 30,000 miles ago and the wires look fine. But, the previous owner had a family and got busy in life right after he got the car so it just sat 5-6 days a week and he took it out occasionally. Could that have had an effect on the misfire.

thanks guys. Really appreciate if you can help me.
 

Black*Death

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Mar 17, 2008
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Idle air control(IAC) or simply a vacuum leak.? I replaced my IAC when I had similar issues. Improved but also really improved when I change my EGR valve. Car would start fine then after it warmed up, misfires and stumbled a lot.

Also check to make sure no vacuum lines popped off or have holes/dry rotted.
 

01yellercobra

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I agree on the IAC. I'd check the plugs as well. Depending on what kind the PO went with they might be worn out.
 

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