Start with an astable (555 or something else) that runs at 2Hz (Period=0.5sec).
Now add a four-bit binary CMOS counter(like a MC14161), wired to reset when it reaches the sixteenth state, meaning that it counts 0-14, 0-14,0-14, forever.
Now, add a four line to one-of-sixteen decoder (like a MC14514).
Out0 drives mot1 reverse
A four input OR gate ( like a MC14072) wired to Out1-4 drives mot1 forward.
Out5 drives mot2 reverse
A four input OR gate wired to Out6-9 drives mot2 forward.
Out10 drives mot3 reverse
A four input OR gate wired to Out11-14 drives mot3 forward, at which point the counter resets back to zero, and the cycle begins again. Each motor period is either one clock period or four clock periods.
You will need to add power FETs between the CMOS outputs and the motor windings.
This could also be done with a modest PIC.