94 E320 W124 M104 Code 5 & 7 - Hesitation, Bucking, Rough Idle

[Synd]

Hello folks!

I recently picked up a 94 E320 locally. The vehicle has about 150k miles on it but is in good shape and seemingly well maintained.

Within 2 months of purchase it threw a check engine light. I used the code check process of clicking the button under the hood to pull the codes. I pulled codes 2, 5, and 7. I replaced the o2 sensor to fix code 2. It did not fix the symptoms:
- Vehicle hesitates under load, especially at lower RPMs. Once it reaches higher RPMs the hesitation begins to minimize which causes a sudden surge of power. Seems to be misfire.
- Very rough idle, especially before it warms up, this causes a light bucking while in drive with the foot on the brake.
- Occassionaly there is what sounds to be a light backfire.

Other than that the vehicle drives well and recently went on a 300 mile trip where it maintains highway speeds just fine.

I'm guessing spark plugs or plug connectors? Suggestions on how to/what to parts to replace with each of those if you agree?

Thanks!