Running badly, stalling, no power when accelerating

Hello so I have a Golf MK1 cabriolet GTI 1.8 with the Bosch K-Jetronic injection system and the car is running really badly used to be ok a couple of weeks ago the idle always struggled in startup but after 5 mins car would be fine. Just took it for its first MOT in 10 years and I few minor things popped up but since taking it out it's been running really badly.

I have changed oil, oil filter, fuel filter under bonnet, and spark plugs 1 and 2 were fine 3 and 4 had black carbon. Looked at dizzy cap and rotor arm contact points they don't seem bad.

Any help or tips would be much appreciated this is my first project car so I'm still learning as I go along, thanks!

Hey Jon,

I am not an expert of K-Jet, but what i do understand is that the metal fuel pipes corrode from the inside and block the fuel system.

Are you getting any smoke or other symptoms?