I am in Florida and have a 1990 190E 2.6. I have had the car for about a year and it has 206,000 miles on it. Within the last few days when you mash the gas the car hesitates, sputters, backfires and then eventually it will stall. If you let up on the gas and push it easy it will gradually build up and go just fine, but once you slow down it does it all over again. This problem only happens when the car is at temperature. Before this happened the car would not start all the time. I pulled the plugs and they were gunked up with ash, so I replaced them. I also put fuel injector cleaner with 93 octane in it. Now the car starts fine, but I have the new problem that I just mentioned above. Any ideas what the problem could be?