I think this is the newsgroup traditionally used for appliance questions, so hopefully this is acceptably on-target.
The Kenmore-branded Whirpool dryer (110.79912900) hasn't been doing well in recent months, taking unacceptably long to dry loads while still clearly putting out some heat. Obviously, the first thing I did was to pull the skins, clean out the usual amount of congealed lint inside the filter screen area, and leaf-blower the entirety of the interior. Happily it is right up against the exterior garage wall with a real short duct to the outside, and that is totally clean.
I observe that when started, the igniter comes on, I get a nice flame for three or four minutes, and then it goes out. But unlike the typical (as I understand it) coil failure, the process repeats, but not for several minutes. No wonder the drying takes so long - the gas should be burning considerably more frequently than I'm observing and it's thus blowing lukewarm air for much of the cycle.
I first thought that this still could be an issue with the coils, and found a web site that tabulated typical resistance values to the various combinations of terminals on the three-post and two-post coils. To my surprise, all were dead on. So I assume the coils are fine.
So now it's time to ask for some assistance. My next thought is the pair of thermostats inside. I haven't pulled them or tested them in any way yet, as they're harder to reach than the coils. Is this a valid next step? Would it be most likely the low-temp (155 degree) thermostat not reacting quickly enough to the drop in temperature after the flame has been turned off?