I know the newer models had WAAAAY more power than the turbo benz of similar years. and fantastic mileage.
popping noise is kind of hard to diagnose in text... perhaps you can record an audio clip or video of the engine with the noise, and post it here?
it could be as simple as a blown exhaust manifold gasket...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!