maybe the mechanic can do an injector balance test to see if your injectors are dropping the same amount of psi's. i know a tech 2 scanner has the ability to do one. you need a fuel pressure gauge connected to the fuel rail then write down each injectors psi to compare them. sometimes if an injector drops more fuel it causes the computer to cut back fuel on all the cylinders on that bank causing misfires.

I agree with bronxtech,

with a bidirectional scan tool you can set the throttle to a given position and then turn each cylinder injector off watching the RPM drop, if all injectors are flowing the same or close to the same the RPM drop will be the same. Look for the cylinders that drop less RPM's than the average of the others, this may be due to clogged injectors, also as bronxtech said you can watch the fuel pressure as you open each injector.

Neal

on the tech2 the procedure is done key on engine off. it powers up the fuel pump to pressure then it starts with cylinder 1 the scanner guides you through all the injectors one by one. re pressurizing after each injector test.

Thank you guys hopefully try this today! Really thank you!