Inducer motor making weird "poof" "poof" noises. The pressure switch on the motor clicks and turns off the flame.

I took the motor out but don't see any water in the outlet header box.

All the drains are clean.

The vent from the outside looks cleans too... has grill and no ice.

When I take out the horizontal exhaust from the inducer motor and let is partially exhaust inside the house it it works better. Mind you it is still still pointed into the exhaust vent but not air tight. This somehow reduces the "poof" of the inducer motor and the pressure switch stays close.

I'm suspecting it has something to do with the exhaust vent, angle of the horizontal exhaust pipe, condensation within it, etc!

I've had several techs come out and I've paid them for their visits, yet no solution.

Any help is appreciated.

Look for a sag in the exhaust line. I had the same issue with mine and the PVC had sagged and allowed condensate water to pool up in the pipe causing backpressure. Realigned the pipe and supported it better. No issues. Also look for a wasp nest, had one of those too!