I bought my truck under the impression that it was in great condition. I changed the spark plugs and had the electric harness cleaned. I believe the truck has a problem with the crankshaft.
I would need more information to know the exact nature of the problem. However, if you believe you are experiencing a problem with the crankshaft, this may show itself as a harmonic vibration that becomes more pronounced when you rev the engine up. If you would like to have your car inspected by a professional, a certified technician from YourMechanic can come to your home or residence in order to diagnose your car and make any needed repairs.