If your cat is clogged will it let the car operate properly while its cold, then cause power loss after its warm?

My car runs 100% until it gets up to tempature.....then it cuts out quickly, stumbling and sputtering, and I have about 1/2 mile to get somewhere till it dies completely and wont restart!

After you let it sit for 30 minutes it will restart, but die again quickly.

 

A clogged cat will be problematic warm or cold as It is restricting the exhaust gas. Sounds like you could have a O2 sensor problem as the car's air/fuel mixture changes when the engine warms up to the point that the O2 sensors are used by the PCM to set AFR.

 

Whats funny is it had a SES light on for the 02 sensor. So I bought the sensor and took it to the shop, but it had an exahust leak right by the o2 sensor. So the welded up the leak and it made the light go off.

However, the "problem" I have developed the SAME DAY I took it from the shop.