You should speak with an attorney in person to see what can be done. Advance parole may be an option for your immediate travel needs.
However, it seems to me that you have a bigger issue - which is getting USCIS to make a decision on your case. It may be possible to file a law suit to compel them to make a decision. This is something that you would want to discuss privately with qualified immigration attorney.
Sue in Federal Court for a Writ of Mandamus to force the government to make a decision on your case.
(213) 394-4554 x0 Mr. Shusterman is a former INS Trial Attorney (1976-82) with over 35 years of immigration experience. His response to your question is general in nature, as not all the facts are known to him. You should retain an attorney experienced in immigration law to review all the facts in your case in order to receive advice specific to your case. Mr. Shusterman's statement above does not create an attorney/client relationship.