To protect yourself, add these clauses:
It is agreed between buyer and seller that:

• If lender is unable to perform by the closing date, this agreement will terminate and earnest money will be refunded to buyer
• Buyer will be given a 24 hour review period before signing any loan docs. If buyer is not given at least a 24 hour review period, buyer reserves the right to terminate this agreement, and get a refund of earnest money
• If the conditions on loan docs differ by what is spelled out in the Good Faith Estimate (GFE), buyer reserves the right to terminate this agreement, and get a refund of earnest money
• In case of a lawsuit, the prevailing party will be entitled to attorney fees

In addition use the neighborhood contingency to find a loan that meets your requirements.