On my 93 sc300 automatic with 136,xxx miles I've had a few problems. When i start the car (this doesn't happen every time) the rpms will boost up to 2000 go back down to close to nothing and seem like it might cut off but then revs back up to 2000 range. this repeats until i hit the gas and pull off myself and it does it when I'm driving sometimes as well. even when I'm braking sometimes it'll speed up on its own, This only happens in first few minutes of starting car. Also my car hesitates and stalls when i accelerate from stop. The rpms will drop and the car won't react to me accelerating at first then it speeds off. This occurs almost every time now only time it doesn't is when i accelerate slower than average and even sometimes it still occurs. I blew a head gasket last summer and fixed it with Blue devil. Also just changed the spark plugs to Ngk iridium plugs. Please help me i want to keep this car because i do love the way it looks so i need to fix these problems i have daily!! Thanks in advance