can anyone help me here. I have a problem with my idle.

When I start up the car, it gives a real lumpy idle. I cannot adjust the idle speed. I f i take out the idle screw, it will then idle around 2k , replace it and it is shite again. I thought the car would cut out when the screw was taken out

Also , when i disconnect the electromagnetic pressure actuator on the side of the metering head, the idle rises to around 1-1.5k. Plug it back on and it goes like a bag of shite.
at the moment I cannot check my CO level until I get it down for its MOT

once I can get this sorted it will be going to a RR for a set up.
Is my pressure actuator or metering head gubbed?

hope somebody can help.