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Q: trouble code P0172 on 1999 Mercury Cougar

car has a rough idle,gray smoke form the exhast. exhast smells like gas. car has been sitting for 4 years
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first off, sitting that long, the gas is really bad. drain tank, add some good injector cleaner. may have to have injectors cleaned. change oil and filter, fuel filter. code set because fuel bad. may have even damaged oxygen sensor.
replaced the fuel pressure regulator then it threw po175,p1409,po453. the o2 senor had been changed not that long ago. replacedmaf,iac,o2
is fuel pressure ok? gray smoke and gas smell would indicate an injector stuck open dumping fuel into cylinder all the time. find out which cylinder missing, that will probably be bad injector.
I found the cylinder that is misfiring, if I replace the injector and doesn't work, could it be the wiring? Or is it just the fuel injector?
replaced the leaking fuel injector put every thing back to garther so i thank took a hole four min then the light came on and threw ftp code any ideas????
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