Originally Posted by Matrix 1193
Let me clarify my experience a little bit here. I was not getting a CEL when the car has an anomalous shudder at cruise, 80 MPH 3300 RPM. I have been calling this a misfire. This may not be correct but to the best of my knowledge i think thats whats happening. It usually happens after I let up off the throttle a little. I never get a CEL when this happens. On one occasion I had my data logger on and could not find anything on there, no spark retard or exessively high knock voltage.
I see some sudden fuel dips and spikes in your 85mmHg and 10mmHg load sites right around 3300 rpm. You really have to make sure everything is smooth and linear in these transistions. I'm 99% sure that is your culprit.
You can also try secondly turning off your "decel cut" and let me know if this fixes the problem. If it does then you will have to make adjustments to the "dynamic enleanment" and "dynamic enrichment." This is unlikely however.