Similar issue with mine recently - had the cowl open so I released the pressure (if any) by disconnecting the sense fuel line from the mechanical pump to the sensor...then I gently tapped on the sensor. Similar issue with mine recently - had the cowl open so I released the pressure (if any) by disconnecting the sense fuel line from the mechanical pump to the sensor...then I gently tapped on the sensor. Things returned to normal. Next flight was fine...next one had the PSI elevated until after warm-up and take-off.

I have also recently had an issue with the AN-6 sized fuel inlet finger strainer (50 micron - I think) being clogged with a fine black substance. It is after the outlet from the mechanical pump - if some of that has migrated up to the fuel pressure sensor, it could be causing this type of failure mode. I'm adding another more easily serviceable filter in front of that which will be part of the annual inspection sequence

I'll be taking mine off this weekend as part of an oil change cycle - I'll try to clean it. I think the best I'll be able to do though is rinse it out as the sensor intake hole is small. Probably going to order a spare sensor - just in case....remembering there are at least two types of high pressure FI applicable sensors - I have the newer VDO/silver/80PSI...replacing the earlier SW/gold/60PSI unit a couple of years ago.

I'll post cleaning and post-cleaning flight results here as it might be pertinent.

Hope this helps,
Ralph