Alright... I have the same engine as a 99+ Mustang V6... (for the most part anyway) in my work truck. Sometimes the needles like to go insane. The other day the speedo stuck at 40, so I'm cruising in a 45 limit and I'm like fuck, not going the limit so I throttle it. Look down, still at 40. So I hit the dash and the needles pop to where they should be and I'm doing 60. Everynow and then they'll just flop all over the place, sometimes they'll stick etc. Is this a mechanical issue with the gauges? VSS or any other sensors? ECU problem perhaps? Give me some insight before I wander into work and let my dad know.