Missouri (MO) - car title and quit claim deed questions

I have a divorce decree that states we are to give each other a gift affidavit for the cars. We've done that and I have taken my x-husband off the title through the Missouri Motor Vehicle Dept. My x-husband has not done that yet, even though I have given him the gift affidavit. My question is: Does the car have to be paid off for him to get my name off the title? Also, he was supposed to sell the house but instead assumed the loan. He was supposed to pay me $6700 and pay his car loan off when the house sold. He no longer has it up for sale and my question is: Since he assumed the loan, do I have a legal right to take him back to court for the money he owes me? He says he doesn't have to pay until the house sells.
thanks for your time and I look forward to hearing from you.

I live in Missouri and the divorce was final in Missouri in June of 2010.

[AFFA]

I wish to inform you that if your ex willfully does not follow court order or neglects to follow court order then you may go to court and contempt of court proceedings will be instituted against your ex. If court has ordered payment of amount then that amount must be paid to you. In his regard your husband must show that he has made efforts for sale of house and if no effort has been made then he has willfully neglected court order and may be held guilty for contempt of court.

AFF