In most cases, if the crankshaft position sensor is bad, the vehicle will not restart after turning it off. So, you could have an intermittent issue with it, but I don't feel it would cause a backfiring issue.
A backfire is usually the result of either an extremely lean fuel mixture (not enough fuel), or an overly rich fuel mixture (too much fuel). Either of these conditions can cause a poor idle or rough running condition.
Take a look through this link for a better description:
Also, is the check engine light staying on? If it is, have the computer scanned for codes that may help. If you don't have a scanner and the vehicle is drivable, most parts stores will do it for you free of charge.
If codes are found, let me know what they are. Also, if you do have a scanner that can read live data, let me know what the short-term fuel trims are.
Let me know if this helps answer your questions or if I can help in any way.
Tuesday, March 29th, 2022 AT 7:49 PM