Hey I am new to forums and I have got a 1989 300sel I am having problems getting it to pass emissions tested due to it running rich it’s in good condition and drives well besides the fact occasionally it’ll lung or boggle at acceleration as well as it won’t start the first crank but second or third I have read about it here and there but no definitive answer was wondering if I could get some help I’m new to Mercedes and am trying to learn

I’ve used a spark plug test light to make sure no misfire and it is good I’ve gotten a new fuel pump and filter but no avail as well as a new ignition coil

I read that there could be a leak or faulty cold start injector so I disconnected the fuel line to only the cold start injector only change is it made it harder to start

Any help is greatly appreciated