just bought an 05 xa and as i was driving down the highway today a pulsing humm was coming from the engine at 75+mph humm...........humm..........humm...........humm..........humm...........etc. when i let off the gas it would stop. would not make a hum under 70 mph. any ony know what might be causing this??? thanks in advance

 

Beats me... you sure it isn't just the exhaust note ebbing and flowing?

 

it's the motor almost blowing up

 

Your wife giving you road head?