My 97 recently started blowing smoke when I get on the throttle more than about 50%.
I pulled the plugs and they looked like they were a little worn so I replaced them and the plug wires with NGKs. This seemed to reduce the size of the cloud, but I'm still killin skeeters when I get on the gas.
I tested the resistance on the coil packs and they checked out fine.
I did replace the exhaust manifold with a header shortly before this started happening, but it was a couple of weeks between the time the header was installed and the smoke started appearing.
I have always had a little black stuff around the exhaust on the rear bumper, but since it has started this it is worse than ever.