bogs down, engine changes tone

What is your question?

When driving, the car engine will change tones and sound like it's bogged down. Thought the converter was clogging, removed it from the picture for now, but still doing it. When you come to a stop the car almost wants to die. When you get up to about 50, the car will shake. it does need new muffler, both are split open, but don't want to waste money on those till problem is fixed. No check engine lights are coming on. any ideas? bad fuel? trany acting up? ignition problem? plugs and wires are less then 6k miles old, AC-Delco parts