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Q: rough idle and dies when you give it gas it either revs up and hiccups or just dies

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i have an 89 f150 xlt lariat 5.0 efi. we were having some problems with it starting and backfiring and we suspected timing was the problem. we put new timing chain in it did everything perfect. fired up for about 4-5 mins died wouldnt start again new plugs wires coil pack starter fuel pump and fuel regulator. still didnt want to start back up. we checked the firing order and how the pumps were ran and they were all ran fine. put in new distributor got everything lined up perfect. started and idles but idle was rough and when you hit the gas it will either rev up but hiccups and sputters and backfires sometimes. flashed my codes got map sensor tps sensor and idle air valve. replaced map and tps cleaned idle air valve. still doing the same thing. all codes are gone. also tested the injector pluse was fine.

all new-plugs,wires,full distributor,coil pack,starter,fuel pump,fuel filter,fuel regulator,timing chain set,temps sensor tps,cleaned idle air valve,map
My car has a manual transmission.

A: Hi there. I would start with a compression ...

Hi there. I would start with a compression test. It is common for there to be a valve issue with one or multiple valves with bad seats which will cause this. If it passes the compression test then the timing needs to be checked with a timing light to see how it is moving when the engine is revved. I have had computers fail on this truck and end up adjusting the timing in the wrong direction. If you are looking to have this timing issue checked, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose why it is backfiring.

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