We have a 2005 rx that is driving us insane, and broke. At approx. 40K miles the car would begin shutting itself off after 30-45 minutes of run time....after 2-3 minutes of cranking it would start and run normally. Initially, this occurred every 1-2k miles, but became more frequent. Dealer couldn'tfind the problem, but suspected the fuel pump, which I replaced with no change. New plugs, crankshaft positioning sensor followed, also to no effect. Now we're at 80k and every time the car is driven it will shut itself off, sometimes taking an hour to restart.

The dealer now wants to replace the catalytic convertor.

The engine shuts off after driving and then slowing down, such as at a stop light.

Suggestions? Many thanks in advance.

 

I could be the Cat getting hot and restricting the exhaust flow. It also could be the engine has low compression.
The cat has a 8/80k warranty. Are you over 80k? If you are, get a midpipe w/resonator or a hi flow cat pipe. They will be cheaper than a new oem cat. Some times cats go up for sale in our classifieds section. Keep an eye out for any of the above that come up for sale.