Q: misfire on cylinder 4

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I replaced the coilpack, plugs, wires, o2 sensor, map sensor, egr valve, had compression test Done getting same in all getting spark car starts up fine on first try no problem starting just runs a little rough from the misfire and hesitates on acceleration on hill I've had diagnostics done 3 times no one can figure it out I'm tired of keep paying for no reason and still got same problem service engine light on and rough idle

My car has 168770 miles.
My car has an automatic transmission.

You had everything serviced except the one thing that will fix the problem. The problem is your central sequential fuel injection system has a clogged or defective injector to the number 4 cylinder. Following the manufacture technical service bulletin 00-66-04-00-30 dated Jan. 30 2003. This TSB details a special process to try and clear out the stuck injectors using high pressure of 150psi and then cleaning them with top engine cleaner. If after the cleaning the injectors do not get unclogged then the system will need to be upgraded from CSFI to MFI following the procedures in the technical bulletin. If you end up needing to have the fuel system upgraded, the professionals available through YourMechanic would be able to perform this for you.

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