Car started missing and losing power. Got it home have changed spark plugs egr valve pcv valve checked convertor done compression test and still now change. Car sounds horrible and runs horrible. Have also checked coils and for vacuum leaks
Hopefully, there are diagnostic trouble codes stored. If not, a scope (for instance, an oscilloscope) diagnostic is needed to see exactly what is going on within each cylinder. With a scope you can determine if you have a random lean misfire, which points to an air leak or fuel supply issue, or you could have an issue related to just one or a couple cylinders.
Without such a diagnostic, you could check out the more common faults on that engine including a defective Delta Pressure Feedback EGR (DPFE) sensor, problems with the Variable Valve Timing solenoid, a dirty mass airflow sensor, vacuum leaks in the intake manifold or vacuum connections.
Regarding vacuum leaks, a smoke machine is often required to find vacuum leaks in the intake plumbing. Another possibility is problems in the fuel delivery system such as a restriction in the fuel pump (there is no serviceable fuel "filter" on your model) or inadequate fuel pump pressure and regulation. A scope would help rule out or confirm such issues.
I recommend having a certified mechanic, such as one from YourMechanic, perform an inspection to determine why your car is losing power and suggest any necessary repairs.
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