I suspect as the program runs through the loop, both ‘else’ sections are being executed and turning the motor off, hence the pulsing.
You could fix this by adding an ‘if C low’ in the else section of the if A statement.
Alternatively, you could change the program so it deals with the four combinations of each input separately. So for motor 1:
A: HI C: LO — Motor 1 Forwards
A: LO C: HI — Motor 1 Reverse
A: LO C: LO — Motor 1 Stop
A: HI C: HI — Motor 1 Stop (or could set forward)
I’ve just enabled attachments, so you can now upload your program. I’ll try and attach and image now…
Hope this helps!