I don't know if the fuel injection cleaner has anything to do with it, but I'd first look at your spark plug wires and the engine wiring harness.
Do you know if the engine wiring harness has been replaced yet?
Do a search on "wiring harness" and read away.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".