Gas dryer won't stay on more than 90 secs

I have replaced the thermal fuse (when it wouldn’t work at all), then the the valve coils (solenoid) along with the dryer cycle thermostat (I think that’s the name of it. It is right next to the thermal fuse). It is still acting the same. Gas comes on for one minute, then shuts off. Then it comes back on after 40 seconds, then repeat, repeat. Not getting the clothes dried very quickly. Could it be the cycle switch? the gas valve itself?