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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 23821
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Ron, I have a 2003 ford explorer with the 4.6 V8. It has

Customer Question

I have a 2003 ford explorer with the 4.6 V8. It has 105K miles. It will start, idle fine for a little while then start missing. When you give it gas it bogs down (almost sounds like it is limiting the RPMs and has no power-barely enough to move. When it first did this it had a check engine light which was a misfire code - we replaced the coils and plugs- no luck. The code cycled out while we worked on it and doesn't show any more. We then replaced the throttle position sensor-no luck.
Any thoughts?
Submitted: 1 year ago.
Category: Ford
Expert:  Derek Werner replied 1 year ago.

Hello and thanks for using JustAnswer!

I am Derek, ASE master technician i will be happy to assist you with your question.

The next best test to perform is checking for proper fuel pressure. Low pressure will cause a misfire concern and a lack of power.

You will need a fuel pressure gauge, this can be found at most automotive parts stores. The gauge connects to a test port on the fuel rail.

Fuel pressure should be between 50 and 70 psi.

Also i would recommend cleaning the mass air flow sensor.