The ignition module on my car puked it's guts all over the inner fender.
Anyone have experience with cleaning that stuff up?
What works best to get it off?

That's nasty stuff to clean up. Most mild solvents don't do much. Stronger (lacquer/acetone) will work, but not so good on the paint there.
You might try Spirits with a softer scouring pad. May require some elbow work, but time consuming.
I sealed the rears of some I had with Glyptol coating.

Heat can help soften it, and acetone will clean it up, but your paint is at risk. So use heat to soften, and something easier on paint as mentioned.

Steam cleaner.

That will certainly softer it, but problem is removing the residue of it.

Thanks for the ideas.
I used a heat gun to warm it up and then used one of those nylon tools for removing trim panels to scrape off the worst of it.
I then used some mineral spirits to remove the residue. It took a little scrubbing but seemed to work ok and it does not appear to have damaged the paint.

Good to hear.

I soaked some shavings of that potting in 4 or 5 different solvents I had in the shop to see what might dissolve it (I skipped lacquer thinner because I didn't want to destroy the paint). Nothing was highly effective but plain ole gasoline was the best. I used gas in a squirt bottle and a plastic putty knife. And a LOT of tedious, careful scraping. Took an hour plus, but I got it all off.