I have a 1992 200TE estate. It has 107,000 miles and is in great condition. There is one problem and that is that the car sometimes has a severe lack of performance when accellerating. Sometimes when the car is cold it is fine. When it heats up or on hotter days it can sometimes take 4 or 5 seconds for the car to respond properly when you press the accellerator. A new exhaust was fited last year. The fuel injection and carburettor were checked and are ok. The auto gearbox was tested and does not apper to be at fault. There is no air flow meter. I have replaced a broken vacuum value and a cracked breather hose, but nothing has made any difference. I have now been to 4 different mechanics and have not yet found the problem. I really need some suggestions as to what could be causing this. When you press the accellerator sometimes the car seems to draw back and not respond and then suddenly a few seconds later it engages and accellerates. Feels similar to driving a car with a manual choke fully open.

please help.