misfire in all cylinders

I would not drive this with CEL blinking. You will ruin your catalytic converters. Fuel filter I believe is in tank with pump. Is this the only codes? P0301 thru P0306? There generally is another or other codes that when fixed, fixes the other 6 misfire codes. Large vacuum leak causing too much fuel to be dumped into engine? Any vacuum hoses disconnected? Not thinking timing. Runs smooth when first started because a cold engine uses more gas. As it heats up it leans out the fuel on a correctly running engine. You have too much fuel being dumped. Manifold gasket leak? P0170 code? 174 code? Unburned fuel is getting to your catalytic converters causing them to potentially be ruined.

Sounds like it's starving for fuel, that will cause random misfires. Check fuel pressure

How long has check engine light been on? Months? years? Thinking bad O2 sensors also. I believe you have 4 on this vehicle 2 upper and 2 lower. I own Toyotas and they need A/F and O2 sensors every 80K or so. I have a 2002 sienna that I keep fresh sensors in. It keeps my money in my pocket instead of in converters. I order and install myself. Denso only.

Irod: I was wondering that myself if it was a P0300? But blinking CEL is always too much fuel.

He said all cylinders not random from his wording. That's why I asked if there was any other codes.

po301 po300,302,303, 304,305,306, and po356, ignition coil F primary. but now it' sounds like clicking and banging inside the head. it's sounds much worse and has barely any power. sounds like something is banging around in the engine. i think its done.

I read several accounts of this and they said one coil made it all better. I would take out and do a visual on coil #6 and inside of plug well. You could also replace harness as this is a possible cause. Check resistance on wire before replacing? I would only replace with a Denso part. I did some research on this last night and several have had your experience.

thank you for the info. and your time. I appreciate it.

When you get this resolved, will you post the fix? Thanks

I just recently had to replace my knock sensor harness on my 02 sienna. I did not drive it before fix. I did go ahead and replace both knock sensors and bypass coolant hose while I had it all apart. From codes, a harness will make all them misfire if in a string with other coils and plugs. I had high resistance in my harness and it was due to being down in V of engine with heat. Yours is most likely heat related also. Might sound crazy but have you tried a junk yard with a low mileage wrecked model that you can pull these parts if you think you have catastrophic failure? It might just fix it and you can buy new after you see what it does...