m20b27 engine stuttering and holding back, temperature jumps

[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 constant speed it sometimes feels like it's holding back as well.
Engine does manage to pull through the revs but a half gas it's worse than when I floor the throttle.
During this stuttering the temperature needle spikes to about 3 quarter, so just before the red area, but the strange thing is that is jumps to high instead of creeping.
Another strange thing, when I shift gear, the temperature jumps back to the middle sometimes.
With no load the engine revs freely.

I suspect a fault in the engine loom, a shortage or bad connection, but maybe someone has experienced similar problems.
Anyone has a clue to where to look first?

[redlightpete]

Check the circular connector under the intake manifold. It contains the injector wiring and the temp sensors, so when the engine is moving under load, you’ll get intermittent misfires and temperature readings. Coolant leaks at the throttle body tend to leak onto this connector and corrode it.

[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.