Furnace randomly shuts off

[Agyuker]

Hello,

Wondering if anyone could tell me what could be causing my furnace to shut off randomly. I had 2 different professionals look at it and fixed various things but it will still shut off randomly. Today it's on and off, it was running fine yesterday.

In service call 1: high limit missing and a jumper in place
called supplier to find out the right high limit for the
furnace. found one and installed it but It still wouldn't work. Also found the airflow low. found the run capacitor low, replaced it too. checked the A coil which was blocked. checked the blower and that was completely filled with dryer lint.
Cleaned it all out and ran it.
It was working fine and was providing the correct temperature.
Was called back after 8:30 and It was out again. found that the unit would randomly shut off, tried to relight but would not open the gas valve. It would lockout and run the fan. Then Found a bad board. Changed out board and igniter with kit and ran furnace. Everything looked good, ran two cycles to check order of operation.

Issue returns after several days.

Service call 2: tested flame sensor 1.5 micro amps, cleaned and retested at 3.6. Fired and cycled ok.

2 days later issue returns.

[samihabib]

It could have a bad ground connection

[Admin]

And sometimes a pressure switch can open right before the gas valve would get power, so check to make sure there is no water backing up in the venting or drain line.

What is the model # of the furnace?