Hello everyone, I have a 2001 c180 Auto 2 litre coupe. Recently I noticed something strange with my car. Other day I drove the car for 50 miles on motorway, entered a city and stopped at the trafiic lights. When the lights went green I tried to move, but it appears no matter how much gas I press, my car does not move off expectdly ( it moves but very slowly like having a hickup and seems like it doesnt have enough power). After a second or so while I am keep pressing gas the car moves off smoothly as normal. It happened twice on two consequtive traffic lights. Seeing that I decided to pull over immidiately and check. everything under the bonet seems normal (no burning smells or no funny indications on trip computer). After and hour or so I started the car again and drove off normally.....after that incident nothing happened for few weeks [normal]. Thinking that might be a resullt of bad spark i serviced my car last week. But yesterday again I drove for around 10 miles on dual carriageway and stooped at a traffic light and it happened again!! it happened twice similiar to last time and then I pulled over because i was at my destination. After an hour I started the car and it ran smoothly!! This time I also noticed immidiately after the phenomena no matter how much gas I press,my car doesnt seems to shift gear properly [I mean auto gear shifting from 1st to 2nd]. I do know if it is related to the first problem or not.....I am not a car techy guy and know little about the car. I will take it to a garage but first I wanted to gather some ideas on what could be the cause of problem....your help is appreciated...

BTW on another note: For the month, I noticed a strange secondary sound from my engine when I press gas. Its like a ratting chain sound along side with the regular engine noise. It happens only when ever I start pressing gas from release. The sound goes away after a few seconds of keeping the gas pedal down!! Is there anything to worry?

Thanks