2002 Dodge Ram

Engine Performance problem
2002 Dodge Ram V8 Two Wheel Drive Automatic 58845 miles

My truck its been shaking since I bought it. At the beginning I did a tune up, plugs, wires, cap and rotor. But still the same I check for codes and found 3 misfires on 2, 7 and 8. I erased them, ran it and checked again an gave me 4 misfires in cylinders 1, 3, 5, and 8. I did a compression test but everything is normal. I don't think is the injectors because of the different misfires. I'm starting to think is a sensor problem even though I don't get a check engine light. Can you help me?
Walter bernal
October 30, 2008.

Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.

Oct 30, 2008.