TESTING CATALYTIC

The best way to test at catalytic converter is the back pressure test. You will need a special fitting to install in place of the O2 sensor. With the fitting installed and connected to a vacuum/pressure gauge you can now read the exhaust back pressure. The back pressure should not be more that 1.25psi at 1500 rpm with the trans in park. That being said - the problem you are having may be caused by a shorted fuel injector. Try checking the resistance of each injector using an ohm meter - they should all be the same or very close. If you find any that have very low resistance they will need to be replaced. If you find one or more that are shorted it would not be a bad idea to replace all six injectors.