If you're mixing in the rack, your tools probably aren't as exacting as a DAW. Trying to replicate the function of a DAW in Eurorack... ummm... super expensive if possible at all.
I'm not hearing too much mud in my opinion. But here's what to look for. If DC (control voltages, etc.) are leaking into your audio, then you can have issues. Many DAWs like Ableton can remove DC for you. You can also use a sharp high-pass filter on the very bottom of your mix. Start at 20Hz and work your way up.
In electronic music, the kick and the bass often compete for the same space. One timely trick is to duck the bass by side-chaining the kick to a compressor. You can emulate this effect with an envelope follower and a VCA. If you invert the envelope follower and dial it to taste, you should be pretty close.
If you can EQ the rest of your sounds to cut any unnecessary low end from them, that might be helpful too. Again, if you have DC in your hi-hats, snare, etc... problems. There may also be natural occurring low end in all of the other instruments that are muddying up your sound as well... especially mid-range synth sounds. Your kick and bass are pretty greedy animals and will poop mud if anything else is in their low end. :)
It's not bad. If all else fails, find a reasonable mastering engineer to evaluate your track and master it. You can also get pointers from a mastering engineer as they have a keen ear for balanced mixes.