Hesitation after 1/4 temp guage AND constant speed

[Gold_BM]

Hi.

My 2000 SL1 hesitates after it gets up to temp (a hair past the 1/4 mark). Furthermore, this ONLY occurs at constant speed. I solve the hesitation by accelerating.

As the original owner, I have 226K miles.

I just followed Richpins P0410 Secondary Air troubleshooting, and successfully cleaned out all the Carbon in the pipe leading to the intake. The Air Pump runs fine. The outlet of the Diverter valve shows flow, but seems much weaker than what the Pump is pushing before it goes through the Diverter.

I have never replaced the O2 sensors.

Thank you.

Ed