I have a 1999 f150 5.4l that randomly blows the o2 sensor fuse. I have replaced the front sensors and it still does it. it happens pretty much randomly. Sometimes it will blow as soon as I start driving and sometimes it will be Ok for days. It never blows while parked idling so I can't trace it that way. I have even driven it down bumpy roads to see it that will cause it but it did not seem to matter. Very frustrating, I would be grateful if anybody had any clues or insight. Oh yeah, the code says both front sensors. thanks