Issue with Arduino car bot, the servo motor moves randomly also it turns hot pretty quickly
I think you need to do some rigorous testing of the individual functions of your bot.

Step 1: rename your loop function to "loop_temp" which means it won't run, but it will be retained for later.

Step 2: write a new "loop" function, which sets the LeftMotorForward for 1 second, then stop for 1 second.  And observe the results. 

Step 3: repeat Step 2 with LeftMotorBackward, RightMotorForward, etc

Step 4: using serial print, experiment with the output from the sonar to make sure it's delivering the expected results.

Step 5: one at a time introduce your functions and ensure they are each working properly.

Step 6: hopefully you've discovered a bug/fault somewhere, and you can re-introduce your original "loop" function.  Otherwise that function may be the issue.

I've had a look at your code, but don't see anything obviously amiss.  So I'm afraid it may be a process of elimination.