After changing the fuel filter and starting I got this vibration like a cylinder wasn't firing. No smoke or anything just a sound and vibration. Once it warms up its fine. Took it for a drive and ran through the gears wide open and it seemed to fix itself. A week later cold start same thing. I also get an intermittent stall when I first start, or pull up to a light and sit waiting, like it's running fine and just shuts off like I turned the key off. No other fuel issues noticeable. No lights on the dash. Any ideas or suggestions for trouble shooting? Runs fine otherwise.