I have a 1978 450SEL. It was running great until yesterday. I filled it up will gas from Chevron and proceeded unto the freeway. Traveling around 65mph or so. When I lifted my foot off the pedal and then proceeded back onto the pedal the car did not respond like normal. I immediately got off the freeway and pulled over. I could see nothing wrong or lines broken. The car idles fine but when you put your foot on the pedal it acts as though it is not getting enough fuel or too much fuel. Any suggestions would be great! I remember when I did not have the car timed right that it was very sluggish during accelleration.

Thanks!