Regarding hesitation on your 300E
I replaced all the plugs-OE Bosch, distributor/cap, replaced all the fuses and cleaned the contacts in the fuse box, fuel filter/K&N air filter. I also the added a can of BG-44K. Car now runs smooth with no hesitation.
Also, I further replaced all the fuel injector seals-they get hard over time. Replaced one broken vacuum lines/rubber tees, so there is no vacuum leak. Also, found that there was small leak on the vacuum modulator of the automatic transmission. Just replaced the cap on it as it was not leaking any fluid and the rubber tee.
Hope this helps.