Merc 200 problem?

I have a 99 Opti. Similar problems. It turned out to be the injectors. They were defective from the factory. It cost me a lot of fishing time and a lot of money spent at 4 different shops. It seems the injectors would seize up when they got hot. You would have to Ohm them while they were hot to check them . The TPI can fail under heat as well. I used a hair dryer to heat mine and looker for a change in MV output. To be sure Merc will send you information on how to check them.