As has been said the popping noise is probably the door check. See if the little bracket it goes into at the frame end has worn out, the holes were oval shaped on mine and the popping was the pin bouncing back and forth in the hole. The junkyard guys looked at me funny and told me to just take it when I walked up to the counter with a replacement. Tools required consist of (iirc) a 10mm nutdriver or ratchet wrench and a pair of channel lock pliers or visegrips. Put some spray-on lithium grease on the new one (and all the others on the heep while you're at it) to prolong its life.