1995 Honda Civic Timing will not change

I have a 1995 Honda Civic DX and earlier this year the car started to shutter violently. It happened very sudden. While I drive it, when I give it gas it shutter real bad but if I left up and very lightly excelerate, it is softer and easier to handle. I've checked the voltage and signal to the TPS and the voltage to the MAP and everything checks out, timing belt was changed, and new distributer. I have not received a check engine light at this time. It feels as if the timing will not change. At a certain RPM the engine feels smooth, under or above that range then I start to have thoughts of pullling over. I have not checked the crankshaft positioning sensor yet. What is the likely issue with my timing? The computer?