Medeski, Martin and Wood - extremely groovy and funky, but in a quite unique and unusual way, a lot of improvisation going on, giving the songs a jam like feel, with detours every once in a while into weird free jazz or noisy ambient pieces (Medeski, Martin and Wood is probably those of my suggestions that will come closest to something you'll like, judging from your description in the OP):
Power Tools - with Bill Frisell, Melvin Gibbs and Ronald Shannon Jackson, free jazz/jazz rock/fusion group which songs often, thanks to the vibrator drenched guitar of Bill Frisell, has a strange floaty, almost ambient, quality about them (the first track on the linked YouTube list, Strange Meeting, even has quite a bit of a Film Noir vibe going on):
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And then for something straight out weird and more explicitly avantgarde:
John Zorn's Moonchild project - with Mike Patton and Trevor Dunn from Mr. Bungle, Joey Baron on drums, and from the second album in the Moonchild trilogy also John Medeski from Medeski, Martin and Wood:
Last Exit - avantgarde and free jazz super group with Sonny Sharrock, Peter Brötzmann, Ronald Shannon Jackson and Bill Laswell, full frontal attack with all of the members going berzerk on their instruments at full power:
Last Exit's album The Iron Path is slightly less chaotic, sounding a bit more organized, and even has some ambient like sections:
This is probably my favorite Last Exit track:
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Finally this Miles Davis album is great too, but you are probably already familiar with that:
