m20b27 engine stuttering and holding back, temperature jumps

[MWe]

So that plug was cleaned en reassembled, didn’t see much dirt in there. Problem still ongoing unfortunately.
Easy on the gas seems to work, full throttle also less holding back. At half gas or...

[MWe]

Currently checking that one indeed, plug c191 it’s called I think.
Had the similar feeling that might be it but maybe someone experienced the same problems and knows the direct solution.

[MWe]

Currently experiencing a problem with my engine.
It is a m20b27 stroker with 1.3 moronic.

When driving the engine sometimes stutters, most noticeable during acceleration, but during...