I have a 1978 450SEL that when cold (first thing in the morning) starts fine. After driving for a while it tends to be very difficult to start. If you start it right after shutting the engine off it will start right up. If you wait 5 to 10 minutes than it takes several cranks in order to get it started. Some of the suggestions have been made to me from replacing the injectors, cold start valve, and enrichment compensator. Just wondered if there is any way to test these devices before buying new ones???
Any other suggestions would be appreciated!!!