Hello,
If the modulator diaphragm has gone bad, the #6 spark plug may get oil (trans fluid) on it also. It is a bit of work. You will need to remove the transmission mounting plate and allow the transmission to lower itself so that the modulator unit is more accessable. If needed the drive shaft can also be disconnected at the transmission to allow it to lower even further. You may not need to make any adjustments as long as you do not alter the original adjustment.
Disconnect the vacuum line and the three 9mm head bolts. Be careful not to loose the spring inside. The diaphragm can easily be replaced at this point.
Keep us up to date, this is a first time topic on this forum.
After repairs are finished, the car may continue to smoke for some time, as the raw ATF is burned out of the exhaust system!