there are many things that can cause the light to flash
here are the probabilities in order of the chance they are the cause:
1) mainshaft speed sensor on the transmission (like the VSS)
2) lock-up solenoid A
2) lock-up solenoid B
from this point on the chances are slim to none but they are included
4) coolant temp sensor
5) baro sensor
6) throttle position sensor
7) ignition coil
8) ECM
you changed the VSS but it could be the mainshaft speed sensor that looks just like the VSS and has the same function only its on the front end and not the back end of the powerflow.
the problem is that the lockup convertor isn't locking up. its either not getting the 'green light' that the engine is up to temperature and the vehicle up to speed to engage the converter or something in the enging end like a solenoid or a blocked passage is preventing the signal from the ECM to lockup the converter from being executed.
there will be a diagnostic trouble code stored as a blink code in the ECM. you can't use a scan tool to get to it. you have to use the connector under the right side of the dash and jump the two terminals then turn the key on and count the blinks of the check engine light or lf that doesn't work lift up the rug on the passenger side of teh car and count the LED flashes on the ECM. I'm not sure what style you have on your car.
hope that helps
