I was given an 1989 300SE. It had been sitting for several years and had a dead battery. I replaced the battery with one I had and after some trying it started. When I got it home I replaced all the fluids and filters, cap, rotor, and plugs. I filled the tank with gas and a can of injector cleaner and drive it for about 275 miles. Now when I start it in the morning I have to hold the RPM at 2000 to 2500 for a few seconds and gradually bring it down to idle or it will stop running. After this first attempt it refuses to start untill the next morning when I must repeat this procedure. Once its warm and running it starts normally.

Any help or ideas will be appreciated.