i have a Honeywell thermostat, says heat on but the furnace isn’t working. When we shut the furnace off and back on it works fine for a couple of hours.. then back to the same problem. Changed batteries in thermostat.

I had an Amana Air Command 90 gas furnace (model GUC 070B30B) installed in my home Oct. 1990. Serial number is 9007073863. At the beginning of this winter (last Oct or Nov) I replaced the original draft inducer blower motor with a new one - Fasco A189 1/24 HP 115 Volt 3000 RPM Goodman Furnace Draft Inducer Blower. The furnace was working fine, but one day I heard what sounded like water gurgling in the exhaust pipe, and I realized the condenser pump had stopped working. I opened the lower outlet of the inducer blower and a lot of water poured out. After letting the inducer blower drain of water, I turned the furnace back on and it went back to working properly. I ordered a new condenser pump - Little Giant VCMA-20 (model-20ULS). Before the pump arrived, I check the inducer blower every couple of days to make sure any condensation was drained away. In addition, before the pump arrived, a previously scheduled duct cleaning service came to my home to clean out all my duct work and my furnace. The technician cut an "access panel" in my duct work directly above the furnace in order to insert their large vacuum hose. After the cleaning, while the technician was packing up hoses and vacuum lines, he was running the furnace to make sure everything was operational. When he left, at about noon on a Thursday 2 weeks ago, the furnace was working. When I returned home from work Friday evening, the furnace was not working but the inducer motor was running and was very hot. I shut off the electricity to the furnace to stop the inducer motor and allow it to cool. My furnace has not run since then. I managed to get the owner of the duct cleaning service to come back out and inspect my furnace to make sure his technician had not done something to cause the furnace to stop working (like, possibly, getting metal debris into the burner area when cutting the access panel). We could find no evidence of that. But he did notice that my hot surface igniter didn't appear to be getting hot enough, so he recommended changing out that part. I purchased a new White Rodgers Ignitor - 767A-369 - and installed it, but the furnace still didn't work. In installed the new condensation pump, but that made no difference. The furnace still doesn't work. So I've come down to either the problem being either in the ignition control module or the gas valve. The currently installed control module is a White Rodgers Universal Hot Surface Ignition Control - Model 50E47-843. The gas valve is a Goodman C6423501 model. Is this gas valve supposed to receive 24V from the ignition control module, or should it be in the millivolt range? I'm reading about 900 mV during the time period, after the hot surface igniter has been glowing for several seconds, when the gas valve is supposed to open and feed gas to the burners. Also, I purchased a new gas valve from Grainger that's supposed to be a replacement from the now discontinued Goodman valve. The valve I purchased is a Robershaw 720-079 Universal Electronic Ignition Gas Valve Uni-Kit. Is this the correct replacement for the Goodman valve?