I have to accelerate a 1500lb vehicle from zero to 30mph in a distance of five feet.
Using a large pneumatic cylinder. How much force or pull in lbs would be required to do this?

A little over 9000 pounds of force.

To do this calculation first find the required acceleration using the equation v^2 = 2ad and solve for a, but be careful of units - 30 MPH = 44 ft/s. This gives a value for acceleration of 194 ft/s^2. Then the force needed comes from F=ma, and again be careful of units: you convert from lb_m - ft/s^2 to lb_f by dividing by 32.2 lb_m-ft/lb_f -s^2.