1999 4runner 2WD with 3.4L and 207K miles.

Long story short, I have been chasing a chronic CEL with 171 and 303 codes till recently after changing my MAF sensor.

Prior to changing the MAF sensor I'd been able to get rid of the CEL by changing plugs and wires. Then codes came back. Then changed both O2 sensors (air-fuel sensors on CA emission vehicle) after dome tried to steal my catalytic converter and cut a sensor wire. Then codes came back. Until recently changing the MAF.

Now I get an occasional 303, and rarely an intermittent 300, but only under one condition - when she kicks down in cruise control with OD on.

The one constant code has always been the 303. I've not tested the fuel system yet myself, but my shop claims to have tested the fuel pressure a while back and said "it was good"

The weird thing about my CEL condition is if I take it out of CC, and turn off OD going uphill to manually kickdown the gear, the codes will clear on their own.

Anyone experience the same or have any thoughts on this situation?