Takes about 4 hours to dry any load. Have tried different settings. Husband cleaned lint traps, hoses, etc. Gas turns on and shuts off about every couple of minutes. Any ideasa?

Don't always believe a fix because it is very detailed and elaborate. You said that your husband checked the lint traps and ducts so obviously that was not your culprit. Yes, it's a process of elimination and that would have been the first check. Now, if you still have the problem, you need to check your thermostats. You can test them by placing the probes of a multimeter on both terminals, checking for continuity. If you do not have continuity, replace it. Check your High Limit Thermostat, and the cycling thermostat. Im sure you will find that one if them is faulty and replacing it will solve your problem. And be sure to always check and maintain those lint traps and ducts to prevent fire.

Most likely problem is the exhaust is plugged. Lint build up and eventually restricted the humid exhaust air.

To test for this locate the exhaust vent where it exits the house. With the dryer running feel for the air flow. It should be similar to the flow you feel from hair dryer.

Second test is to light load the dryer setting the heat to high and after several minutes of operation open the door and confirm the clothes are hot to the touch.

Hot clothes and no air flow for ever to dry!!

1. Remove hose from wall connection. Confirm vent hose not plugged by running dryer. Very dusty process. If no air step 2.
2. Remove vent hose from back of dryer. Confirm air flow from dryer. Very dusty process. No air step 3.
3. Service dryer blower likely plugged with lint. If dryer basket turns I would assume blower is also turning connected by drive belt. The blockage internal to dryer.
4. So if not 1,2 or 3 than blocked vent hose to the outside . Suggest using a vacuum hose to carefully try to retrieve lint build up. Lets hope that it is not a roof vent because it would really suck trying to pull the blockage out. And unless your Santa roof tops are dangerous places to play.
5. Well at least at this point we know why the clothes are not getting dry. What ever you do do not breach the venting in the walls. Moisture will build up along with the lint and create havic with mold!!!
6. Call your husband

Sounds pretty busted, would recommend seeing if it is still under warranty if not, you might need to make an investment in another..