If you tested them the way I think you mean, it's very short term and cats should cope. Leave 30 secs between each test (tough not to). Changing them as you did takes away a whole uncertainty issue at quite low cost. Cheap peace of mind. Plugs as well or not due yet?

 

I have done plugs as well,they had another 10k before they needed changing according to book ( its amazing how long they last nowadays)and looked very good for 60k

 

So the tech suggested that we replace 3 coil packs in total, and all the plugs, and I authorized him to go ahead. Wow, big difference! The engine is running and idling smoothly, and the gear hunting has disappeared. As to the hard starting, it is still happening, but less frequently. The fuel pressure checks out OK even during hard starting, and the fuel filter has been replaced, which brings up an interesting issue: there was a noise on take-off that I assumed was a belt or pump-bearing problem, but now appears to be coming from a bent or cracked transmission flex plate (urgh...). The shop master mechanic's theory on the intermittent hard starting is that maybe the bent flex plate is affecting the position of the crank sensor on starting. I'm inclined to believe this, as I had an '84 Alfa Spider that had a similar problem -- a cracked bell housing affected the position of the sensor, leading to intermittent starting problems that got worse and worse (as the crack expanded) until the car simply wouldn't start. Of course, now that I know where the noise is coming from, and the engine is much more smooth and quiet, I hear the damned flex plate noise all the time, annoying me to no end. I can live with occasional hard starting, but not that darned racket! A transmission rebuild was done in July by the administrator of the estate (I inherited the car), with a 12 month warranty, but by a small shop in Arizona -- I'd have to drive the car back there to have warranty work done. Dropping the transmission and replacing the flex plate is well beyond my skill level, tool collection, and working space, so a DYI fix is out of the question. So, the question is: is it worth contacting the AZ transmission shop, driving back to Phoenix from San Francisco, and hanging around in a motel for a day or more while they do the work vs. having the work done here for real money? If so, I'm probably game. On the other hand, I have no idea if a flex plate is even covered in a transmission rebuild warranty, as it does seem to be sort of separate from the box itself (though you'd think its the sort of thing the rebuilder would have checked out). I'm open to suggestions...