I have a 940GLE - 230F engine. #4 cylinder is not operational at idle, usually when the engine is warm. I changed spark plugs, wires and dist. cap. I also checked resistance @ control unit (4.3ohms). Also each injector individually read (5.3ohms). At high RPM the engine runs fine and is within normal parameters. However when I stop at a light it runs as a diesel engine, in gear or not. I heard that injectors are a rare failure, are reliable. Is there anything else I should check before chenging the injector? Will that fix the problem? Thank you in advance for any helpful tips.

Assuming your valves are not way out of adjustment, then either the ignition is at fault or the injector. If you changed the ignition parts and get a spark, then suspect the injector.