Toyota Repair: Camry misfire, throttle position sensor, valve piston

Question
Hi Ted I hope you can help me out…
I got a 1998 TOYOTA Camry LE V6 W/170K Miles
The problem is that in the auto shop they can’t correct a misfire on cylinders
1, 3 & 5, the scanner gives codes P0301, P0303 & P0305
Here is what has been changed, spark plugs, wires, fuel pump, fuel filter, oil, oil filter
air filter, MAF, throttle position sensor, temperature sensor.
Here is what has been checked, banks 1 & 2 O2 Sensors, timing
belt, valve & piston leaks, the injectors have been cleaned (twice!)
Can it be the ECM…?

Answer
The ECM is the least likely cause for this, all the cylinders on bank one indicate a misfire, the most common cause for this is that the timing is off on bank one, have them recheck the timing again or go somewhere else to have this checked, nothing that has been done so far addresses a misfire on all bank one cylinders, has the timing belt been replaced? Even if it has, the timing has to be checked again, I have seen this happen many times and it's about the only cause for all cylinders to misfire on one bank.