Idles great, severe loss of power under load

Asked by ildiran961 Aug 25, 2022 at 06:00 AM about the 2000 Mercury Grand Marquis GS

Question type: Maintenance & Repair

I have a 2000 Grand Marquis and just replaced the intake manifold after it sat, not running for 18 months. The car starts and idles beautifully, but on the test drive, it lost almost all power when trying to accelerate. I'm thinking it's a clogged converter, but was wondering what else to check besides a vacuum leak. The CEL buld does work, but it hasn't come on and no codes are present (which is definitely confusing, considering how poorly it was running).

2 Answers
310,265

Gene answered 2 years ago

A vacuum leak will make the idle high on this type pf system so I doubt you have one. You can get a back pressure test kit from most parts stores for the exhaust, it can't run right if it can't breathe, also make sure the fresh air intake is not restricted.

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157,625

James answered 2 years ago

Also, after sitting for 18 months you might have water condensation in the gas tank. Put a bottle of Drygas or similar product in the gas tank and fill it up. Hopefully that's all it is. Hope that helps! Jim

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