fuel trim

Having an odd issue right now. LTFT both banks are going to +20 when cruising down the road at part throttle. I also get sporadic spark knock when im crusing at 2k rpm and lean into the trottle. They normalize when I go 50% or more throttle. I currently run E85 and have verified 85%. I have...

Setup is 2016 GT, 2.9L Whipple, ID1000, KB BAP, 132MM. Been installed since 400 miles, car now has 26K. For almost 2 weeks now, I've been having fuel trim issues. It all started ( I think ) Wednesday before last. Fueled up with Shell 93, from a station I don't often use. Stopped to grab food...