Q: Engine stuttering in acceleration.

asked by

Justin H

on March 10, 2018

For starters, car has trouble codes PO300, PO304 and PO420. the engine is stuttering in acceleration and seems to be worse when the engine is warm. Sometimes, I can press on the gas and it will not go any faster until whatever is wrong fixes itself and then it will be fine. It does not do it every time but it has a hesitation when it comes to pressing on the gas. For various other diagnostics and car maintenance, I have replaced the spark plugs, spark plug wires and boots, engine coil packs, EGR valve, EGR modulator, purge solenoid, vacuum control valve, vacuum switch valve, and most recently the Idle air control valve. I am lost in any further diagnostics and I do not know where to start anymore. I have checked the EVAP hoses for leaks but all of them seem fine. Could this be an issue with the fuel injectors? If anyone could help I would really appreciate any leads on where to diagnose next.

My car has 164000 miles.
My car has an automatic transmission.

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Q: Engine stuttering in acceleration.

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