How to prevent 555 timer interference
I notice from your circuit that the 555 and motors are running from a common (5V) power supply without any form of decoupling. The 555 is a current hog and draws a surge of current from the supply every time its output changes.

Try putting a large electrolytic (say 220uF) and a 0.1uf (helps with high frequencies) across each the Vcc and ground pin of the three 555s.

I would also make the capacitor at pin 5 a bit bigger (say 0.1uF) - its job is to smooth out any noise of the internal divider chain of 5K resistors. 47pF is way too low.