I just did a major job on my 2007 Elantra. Because of a blown head gasket I had the head rebuilt and now everything is back together. The car runs great except that now the engine runs slightly rough. You can feel it most during idle. When you put your hand on the exhaust you can feel a slight puffing instead of a smooth breeze. That's all. Everything else seems perfect and normal. No funny noises, good acceleration, good power, no surges or irregular idle, just a little rough. It's almost like a V-6 or V-8 not firing on one plug. There is no check engine light on. The valve lash of all 16 valves is accurate and near perfect, the timing belt timing marks are dead on target and the timing chain connecting the exhaust cam with the intake cam are also dead on. There are exactly 7 chain links from mark to mark on the cam gears. I must mention that the engine has VVT. The only other thing that I can think of is that the VVT mechanism is not working right and the 2 cams are out of sync, but wouldn't that cause the check engine light to come on? Also the ABS light is on on the dash, but that wouldn't have anything to do with it, would it?