89 integra still putting out a lot of emmmisions

I got an integra with about 250,000 miles on it and so far I've replaced the following:
air filter
plugs
wires
coil
IAC valve
Cat
oil change
The motor runs surprisingly strong with the amount of mileage it has so I think it's worth trying to make it drivable (smogging and registering it). But when it shifts it leaves a smokescreen behind it in little foul smelling clouds. I drove behind my friend driving it so see how bad it was. It's not terrible, just noticable when he shifts. Any idea of what I should work on to get it to stop the smoke and get it to pass smog?

To pass smog, I would recommend putting in some high octane gas (if you already aren't) and/or put in a bottle of "dry gas" in your tank. Run your car a little hard right before you take it to echeck, it would help get some of the carbon out b4 you are tested. That sould due the trick, it's just a temp. solution, but one that sould get you past e-check. :smokin:

What color is the smoke?

it means you have leaks going into the combustion chamber and will cause clouds at the tailpipe.
check your do a compression, check headgasket, piston rings, seals