Deputy of Mayberry
Join Date: Dec 2007
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Usually a clogged cat won't cause idling problems. Just at higher RPM. ...Usually. An exhaust shop should be able to check it. They'll drill a small hole upstream of the cat and hook up a pressure gauge while revving the motor. If pressure builds quickly and takes too much time to fall back down, that indicates a clogged cat.
I'm betting the timing belt slipped. Even though the belt was changed only 30k miles ago. If they didn't replace the idler pulleys or the water pump, those can start to bind up or wobble and cause the belt to skip. Or maybe a really cheap belt was installed? Fairly easy to check it. Remove the upper belt cover, turn the crank over by hand until the ignition timing mark on the crank pulley lines up with "0", then see if the front & rear cam pulley marks are lined up with their index marks.
2015 RAV4 Limited, AWD, tech pkg, Barcelona red metallic, 6k miles
1996 Avalon XLS, ABS brakes, super white II, acquired w/ 139k, now at 326k
1992 Camry LE, V6 (3VZ-FE), ABS brakes, dark emerald pearl, owned since new. Replaced HGs @332k, totaled at 384k miles
Last edited by BMR; 02-09-2013 at 10:38 PM.