I'm an automotive student and have a customer's vehicle that I'm stuck on. It's an 02 MDX that dies when you rev up the motor to anything higher than 3000 RPM and then as it drops down. It doesn't do it often, usually it will simply drop down to about 200-500 rpm then go back to normal 800 idle. Seems to do it more when it's cold, and can't really get it to get that low when warmed up.

Replaced EGR valve, performed a de-carbon service, vacuum is normal for elevation, spark plugs are fine, relative compression test shows great compression, new Denso front O2 sensor, new MAP sensor, misfire counter on an Auto Enginuity scan tool shows roughly 30-60 misfires in a 15-20 minute driving period at varies speeds. IACV seems to be working properly as commanded by the scan tool and also unplugging it the idle increases and goes to normal when plugged in. The car has had this issue for a long time. Previously, it had a CEL for P0300 and P0301-306 so every cylinder misfiring, though currently no misfire DTC's.

Anyone have any insight? I'm completely out of ideas besides doing a valve adjustment, but compression and vacuum show that everything is sealing and perfect. Trying to keep costs low for the customer.