Hello my name is XXXXX XXXXX X will be more than happy to assist you.
The engine oil filter is also the filter for the Oil Control Valve.
What have you done and replaced so far to try to fix the problem?
There is 4 posible causes. Valve Timing, Oil Control Valve, Varible Valve Timing Controller, or Engine Control Module.
Most likely the Oil Control Valve is the cause, but if you have a voltmeter I can walk you though a few test.
Also when was the last time the timing belt was changed?
Serpentine belt and water pump were replaced around 110K. don't know about timing belt but assume around 100K. I can check if it's important.
check-engine light used to come on at various times but always went off according to prior owner but now stays on. I have a multi-meter.
The timing belt is important if it has not been charged ever or it have been over 90,000 miles.
Ok then at this point we will assume the timing is ok.
Go to the Oil Control Valve on the rear cylinder head, Unplug it, turn the voltmeter to 10 OHMs and measure the resistance. What is the reading.