I've been working on my aunt's 05 sienna. It previously had codes for ignition timing over retarded (I think p0022/p0021) also had a code for random misfire p0300. I replaced all spark plugs, both OCV sensors, and cleaned out OCV filters. This fixed the timing codes however I still have the check engine light flashing but not codes with it now. It flashes under load so if it's at idle and I hit the AC switch, the light starts flashing and engine rpm goes up and down like it wants to die. I've driven it around the block (I know I shouldn't) but it's still not giving me codes so I'm not even sure where to start. There doesn't appear to be any vacuum leaks. There was some oil in spark plug #2 but I figured if it was that cylinder misfiring I'd get a code for it. Any help is appreciated.