300e 2.6 gets *Sluggish* at times!

[Miles81_240d]

Hello All,

I have a 92 300e (M103 2.6) w/ 126k...
Its weird!, sometimes the car has brisk acceleration from a standstill, other times, it is *extremely* sluggish during acc. I can floor it literally and it will just slowly gain speed. It acts as if it was (for example), a carburated car that had either "too much gas" [and was choking on the excess fuel], or "too lean" (and not enough gas)... I have replaced the spark plugs, air filter and cleaned the throttle body area of the car.. this sluggish symptom still persists.. BTW- this is a 1992 300e, it does start out in 1st gear. Any opinions? I have not replaced/checked the fuel filter. I have also been wanting to replace spark plug wires and replace dist. cap + rotor ( i suspect them to be original).. would this sound like an ignition or fuel issue? I will say that on occasion the exhaust does smell slightly "rich"..... any theories?? thanks all for your awesome help!

-Miles
92 300e 2.6 126k