TMK44

Looking for advice on how to troubleshoot issues with power door locks. Long story short, both front power door locks stop working after repeated use-- they'll work 1-3 times in rapid succession and then stop working. Then if you wait for about 20-30 seconds they'll work again for another 1-3 times. Below is a summary of findings:

• About a month ago, I tried to lock the doors with the engine running and the driver door open (in order to lock a running vehicle), and I noticed that the driver side door didn't automatically unlock (which is standard operation, presumably a measure to prevent locking the keys in the car.) Since then, I've noticed this behavior on and off. Sometimes the driver door stays locked; other times it unlocks.
• Today, I decided to take a closer lock at the issue and found the behavior described above: power door locks work a few times, then stop working, only to begin working again after a short pause.
• At another point, I noticed that the radio did not shut off after (a.) turning off the ignition, (b.) removing the key, and (c.) opening the driver door. Normally, the radio shuts off when you open the door, provided that (a) and (b) are met. This led me to suspect that an open door sensor might be stuck. (I'm thinking there's a little switch somewhere that gets pressed when you shut the door. I looked but couldn't find one.) --I don't if this is a related issue but decided to mention it.

Anyway, all that said, I'm looking for a procedure to troubleshoot and decide whether this is a DIY project or if I should just put this problem in the hands of a professional. --I usually don't mind rolling up my sleeves and getting my hands dirty if the chances of doing further damage are low. Thanks.