Alright, first post, Sometimes when the engine in my '73 450 SL is hot, just been run on the highway or something where the engine gets particularly hot, when i start the engine, the engine speed will not even register on the tach, run very slowly and make a huge stink. But now the interesting part, if I rev the engine up to 3.5-4.5K it will spool down and run perfectly.

 

it is do to the air temp the moter will run bad. it sounds like the aux fan is not comming on