Edit: Found the link   http://pure-gas.org/

Bad gas (Shell premium though) or condensation in the tank after running it down to the warning light before I had filled it up. Add in the old O2 sensor, a few marginal hoses, older plugs. etc etc???

Still same cel issues this morning, cold and engine warm. Except when going up a steep hill with throttle.

Gas gauge showed about 3/8 of a tank and I hadn't added any since this mess began in case I had to pull the pump. So added a container of HEET, put in 5 gallons of 93 from the local SA. No change for about 10 minutes then I got on the throttle hard, cel blinked for a bit then stopped blinking.

Drove around for about a 1/2 hour fine. Turned it off for about 10 minutes. Started again and ran it again for a 1/2 hour. Side streets and highway. Fine. No cel.

Letting it sit for the rest of the afternoon and we'll see what happens later.

Like I said maybe...

I'll try the new relay.

Could be afm. I've been driving on Milwaukee roads with lowered suspension enough to rattle teeth. Maybe something knocked out of whack.

A quirk in the ecu itself? I've got an extra one I can try.

This uphill on a steep grade though has me curious.

When you hear of a blinking CEL under load with no stored codes that initially makes me think misfire but you say its running good.

Have you tried disconnecting the battery for a few minutes to reset the ECU?

Needed a muffler shop to get the O2 sensor out. On the way home cel would flash but under load up a steep hill doing 35-40 did not flash. Once on a more level grade would flash. This might mean something but I'm not sure what.

Rpm range flash starts around 1500 and will flash up from there. Highest I revved it was over 4k, and still flash.

Swapped out the O2 sensor relay early on but since it didn't make a difference put the original back in. Since the O2 sensor has been changed I'll try th

If it were related to the Main ECU relay having a bad connection/loose relay the car would stumble when it happend
BUT, it may be worth checking into the o2 sensor relay since the car would still operate normally under open loop and perhaps a code for o2 heater voltage or o2 signal wouldnt be stored because the duration of the malfunction isnt long enough. This is just me theorizing and thinking out loud, some ECUs require a certain number of malfunctions within a certain timeframe to store a code and a certain number of start cycles with no malfunctions present to clear the codes so having a time/duration based code storage criteria is something that makes sense to me as a possibility (my theory/me thinking aloud).

I am also curious as to whether it is AFM related, such as a dead spot on the resistor track or a weak spring, or a wiper arm that needs adjustment since a vacuum spike within the intake tract while accelerating could peg out the AFM with one of those problems and cause it to read out of limits.

I'm stumped. Car runs fine. I've got an oil leak at the filter housing maybe this?

I will have to check my parts bin but you are welcome to try it and if it works out for you can have it for $20

Smooth idle cold, after a few minutes stumbles, cel flashes and almost dies. Disconnect O2 sensor and idles smoothly, give it throttle still runs smoothly but cel flashes.

Cel flashes on throttle with or without O2 sensor connected. No codes stored. Think it's time to try a new O2 sensor.

Coil packs check out fine, cps as well, cam sensor, tps and icv, afm (tried with and without the resistor harness).

Replaced fuel filter, spark plugs, intake boot.

Checked plug wires. Resistance on wire 1 is 15.33; wire 2 is 5.76; wire 3 is 5.74; wire 4 is 5.98. Meter set at 20k. Not sure what values should be.

If anyone can think of something I've missed please let me know.