what would be signs & symptoms of a flaky pressur regulator?

[skikir]

I'm having some odd occurrences of uncommanded lean AFRs and wondering AFRs. The pulse width or duty cycle isn't changing but I'm getting lean spikes especially while shifting up the gears.

[LAV1000]

Performance of car stays as it used to be ?

Did have the same issue, lean spikes and no performance drop.
1 day later I noticed (by sound) exhaust was leaking at cillinder head.