I've had this happen before, and I just had to keep jacking. The car seemed like it was raising, and it was, but suddenly it stopped raising and the engine kept going.
You might need to loosen the bracket going from the tranny area to the exhaust pipe. I don't think this is gumming up the works, but it can wedge things up a bit and possibly snap a joint loose on your exhaust, especially with your amount of rust.
