My T34 on greens stage 3 Saph has recently started running lean.
The first symptoms were that it wasn't making the same boost, even though it's on a Gizzmo EBC. I went and had it checked out, and the bad AFR figures were found out.
I now have an AFR gauge on it, and on normal driving it's around the 10s and low 11s, then when boosting it goes to high 14s at 20psi!

It's been on a dyno twice before a while back, and had the AFR checked about 6 months ago on the road, and it was ok then I'm told but I don't have a record of any figures to prove this.

It's just had a new 044, pump rewire, pre pump filter and replacement OE fuel filter fitted which didn't make any difference.
Running out of ideas now!