I see this thread is pretty old but I thought I would post for people who search this in the future. I was having the same issue following timing belt replacement. This was very frustrating, I tested and replaced several sensors before finding the problem. Very low rough idle and stalling after warm up. Plus extra smoke from the exhaust.
I found the cause to be two small vacuum lines were swapped. They were the ones that run from the intake and fuel rail over to the drivers side strut tower. the stock hoses have numbers printed on them (16 and 20 ? from memory). I had these swapped at the shock tower end. with correct routing the numbers should match the hoses at the other end that leads to a couple components in front of the shock tower. They are also shown on the emissions stick on the underside of the hood.
Good luck.