360 stroked to 408. Running issues.

Hi,

Need to know the exact idle AFR and cruise. The AFR at "closed loop" should swing back and forth from 13.5 to 15.0 approx. What is the AFR at Wide Open Throttle (WOT) "open loop"? Should be in the 12.6 AFR plus or minus a tad.

Here is what I recommend. 1. inspect the AFR sensor in your exhaust collector and look for ANY issues. In particular cracked welds or frayed wireds or even burnt harness from exhaust. ANY intrusion of fresh air will skew the input to the ECU. 2. Remove the sensor and look for any "stuff" on the probe. It must be clean! 3. Reset the ECU to "relearn". This will wipe the ecu of any learned timing an fuel correctied tables and start fresh with a new learn. Just like a PC sometimes the software may incur an error and corrupt a file within. 4. Check all the grounds!!! I even added a additional ground from the efi throttle body stud on the mani to the block to assure sufficient grounding. Grounds often go unchecked when things get intermittent or otherwise off.

Try this and report back.

Marion