I have a very annoying misfire / loss of power issue that’s kind of doing my head in

ill start off by saying I am no mechanic but I am more than happy to DIY and solve issues myself -I just lack the knowledge

so my ML55 113 engine has had all its gaskets done - regularly serviced (about 5k between services)

my loss of power happens when on load so over 3k revs. If I keep below that or it’s jus on idle it will run fine

because of my lack of knowledge I have thrown parts at it and now I’d like that game to stop

I understand I could take to a mechanic but actually for me part of the fun is not doing that - it’s not my daily it’s more my project car

So initially I swapped around coil packs coil leads and spark plugs but misfire would stay on cylinder 2. So I thought maybe fuel related and ended up replacing ALL injectors, fuel pump and fuel filter / regulator

now I get random misfires on any cylinders

if I turn the car off and back on all is good and runs fine again for a while until I go over 3k revs

in the meantime I’ve now replaced the camshaft sensor, the crankshaft sensor, the MAP sensor the thermostat and temp sensor. The secondary coolant / water pump. The water pump.

and because I had the dreaded water in footwell due to sunroof drain, it possibly caused O2 sensor issues so I’ve replaced all four O2 sensors

I've replaced all the EGR hoses and checked / cleaned EGR valve. And I also changed the EVAP valve for fuel vapour recycling (I think)

I can’t aee that it’s ignition related cause as I say after a restart it runs fine again. And I’ve swapped round coils and leads and plugs and same result

it can’t be fuel related as I’ve swapped out those parts and also done a pressure check on the Schroeder valve and get constant 52psi even on load and when car is off it holds the psi

guys What am I missing here? What have I overlooked?

as I say it loses the power with load over 3k (but not when sitting in N/Park on idle)

Any help would be much appreciated - as I say I view this like my project car so really would like to sort with your help rather than take to a garage