I had an idle problem where revs dropped to around 600 and the engine shook for a second before returning back to idle. A new air filter sorted that. My short term fuel trim still shows around -7 % but the car goes well. Have you looked at your fuel pressure regulator? If you are weeping fuel into the vacuum pipe your diaphragm has failed and could be the source of your leak. Fuel trims would be positive if fuel pressure was down.