As you may recall I had a furnace that would shut down after running a while. I thought I had tapped the pressure switch, but either I didn't, or did not tap it hard enough, or it just wasn't acting up at the time. So per your advice I tapped it again and it made the burner stutter. I then jumped it out after the burner started up and it ran fine, but acted up as soon as I pulled the jumper off. I went to buy a pressure switch and the tech rep guy at the Trane store was trying to talk me out of buying it, said a good one would do that if you tapped it hard enough. Suggested I should tap the gas valve instead. But I put it in and ran the temp up to 75, jumped out the outdoor stat as it was over its 30 degree setpoint, and it ran almost an hour without any problem.