Gas Hot Air Furnance on/off every 2 minutes

I have a Bard gas hot air furnace that is recycling on and off. It goes on for 2 minutes and then off for 10 minutes on the automatic setting. It stays on when on the manual On setting. The furnance is 15 yrs old, Bard Model IH115D48B

The temperature of the house depending upon the outside temperature is at the setting or a few degrees less than the setting. The day settings very depending upon week or weekend at 64 or 67.

I took out the flame sensor and it looked clean and not sooty but I cleaned it anyway with steel wool and emory cloth. Filter is not clogged. Flame at the igniter looks good and the flames at the bottom all look good. The plastic hose to the pressure switch is not clogged.

What can I test out next, procedure for testing, or what should I replace?

Do limit switches fail often? Pressure switches? Transformers? Where do I go for testing information? I read on the net to take an volt meter to the transformer, ground one, and when the furnace is running, every terminal (5), should read 24 volts. Only 2 of the5 are reading 24 volts, the others are reading 0 when the furnace is running.

Also on this furnace is a box 2"x2"x5" that all the wires clip on and the flame sensor goes to. And there is a small rectangular box with wires that looks like like a relay switch on a car.

I was just near the furnace and I heard a click, sounded like it was coming from the transformer, and it almost sounded like a magnetic relay was opening or closing but nothing happened on the furnance.

Greetings Lawrence welcome to the Forum.

There should be a set of temp sensors down stream from the Furnace, they sense when the Air warm enough to start the Blower, and will shut the unit down, if the Air gets too hot.

It may be that the Overtemp sensor is set too low, but, it doesn't sound right that it would only shut the unit down when it was in Auto mode. Should do it either in Manual or Auto. But that's something to check.
My best guess.

Have a good Day !
S.W.