Big problem: used Bosch Platiinum4+ on 95 E320

Hello, today i tried to replace the spark plugs on my 1995 E320. We were told to get the Bosch Platinum 4+ (the only kind everywhere has), so we replaced the original ones(1 tip) with these platinum ones(4 tips). Then when we started the car it was shaking very badly as in running with 5 cylinders(cannot confirm). So we thought replacing the original ones would work. After putting the old ones back in, the problem did NOT go away. Though twice the engine ran fine, but that never happened again. Since we were only trying to replace the spark plugs we did not touch anything else. Does anyone know what the problem might be? Thanks for you help.