What's Wrong With My Gas Water Heater?

I frequently had to turn off, then back on, my 6-year old ELECTRONIC IGNITION propane water heater. It would often shut off after 3-10 seconds, and I had to repeat the procedure. I noticed a "fluttery" flame, so I blew out the area w/ compressed air and got a lot of crud (corrosion?) out of there. All was well for about a week, but now the problem is (intermittenly) back. Do electronic ignition heaters have a thermocouple? Any other ideas?