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My 2006 3.7L with 140k miles started throwing the dreaded P0300 random misfire code two weeks ago at cold startup. No other codes observed via my Actron CP9690 scan tool. Replaced the crank sensor since it was the first suggested repair based on vehicle mileage and frequency of occurrence in the wild, and cleared the code. Code came back on a cold restart the next morning.

Drove the vehicle all week to near empty, refilled with 93 octane and dumped in a bottle of injector cleaner and drove for a couple hundred miles - No help. I have previously replaced the plugs with Iridiums at 120k when I purchased the vehicle two years ago, and all the plugs that came out looked normal. I have not pulled any of the plugs yet after 20k miles to get a look and see if any of them look abnormal.

Vehicle remains drivable and has not stalled on me, and only misfires at cold startup (very rough idle), acts like it worn't take the gas, then takes off and is fine. Once warmed up, no issues at idle or when driving around town. No issues at high RPM either.

I hate to flail and throw parts at this vehicle undiagnosed. Was thinking of getting the intake checked for leaks by a local mechanic, and then start replacing the plugs one by one.

What do you guys recommend for next steps? Thanks!
 

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My 2006 3.7L with 140k miles started throwing the dreaded P0300 random misfire code two weeks ago at cold startup. No other codes observed via my Actron CP9690 scan tool. Replaced the crank sensor since it was the first suggested repair based on vehicle mileage and frequency of occurrence in the wild, and cleared the code. Code came back on a cold restart the next morning.

Drove the vehicle all week to near empty, refilled with 93 octane and dumped in a bottle of injector cleaner and drove for a couple hundred miles - No help. I have previously replaced the plugs with Iridiums at 120k when I purchased the vehicle two years ago, and all the plugs that came out looked normal. I have not pulled any of the plugs yet after 20k miles to get a look and see if any of them look abnormal.

Vehicle remains drivable and has not stalled on me, and only misfires at cold startup (very rough idle), acts like it worn't take the gas, then takes off and is fine. Once warmed up, no issues at idle or when driving around town. No issues at high RPM either.

I hate to flail and throw parts at this vehicle undiagnosed. Was thinking of getting the intake checked for leaks by a local mechanic, and then start replacing the plugs one by one.

What do you guys recommend for next steps? Thanks!
@Iceman;

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