drove a 95 camry with the exaust's flex pipe broken. Most of the exaust exited the pipe before making its way through the catalytic converter and grime, dust, etc from the road must have built up on the catylitic converter from it being exposed. I got the flex pipe replaced and the car idled really low and stalled out when came to a stop. I messed with the idle air controll valve to make it idle a little higher, and now when I come to a stop the car won't stall but it almost does- it repeadidly revs itself from 150 rpm(where it almost stalls and the electric dies out for a moment and i have no brakes) and up to 750 back and forth. If i pop it in Neutral it will idle fine at 750 but i wait till i'm under 20MPH to pop in Neutral since it's bad for the car to roll fast in N. I don't think its good for the transmision to keep changing it back and forth all the time especially since when I pop it back into D, I try to get the RPM around 750 and if it's higher than 750, it bucks into gear.
I'm assuming i should change the catalitic converter. almost all searches about low idle lead me to idle air controll issues, but it's clearly not the IACV. the cloged cataylytic is cloging the air and forcing it in the wrong direction unless i'm hitting the gas which overpowers the clog?
Can anyone help so i don't waste $ and time on changing the catalytic converter if it could be somethign else. thank you much

Welcome to the forum!

Have you checked for a vacuum leak or engine misfire? When's the last time the car had a tune up? A 1995 could certainly have brittle and cracked vacuum hoses.... Start with the simple stuff first.

Also, you should never muck with the idle speed on a modern car. If the idle is too low, it's not because it needs to be adjusted, it's because there's a sensor, servo, or other mechanical issue.

-Rod

This shoud be moved to the Toyota Camry section. You don't mention the engine size, that can be helpful. Also, post any trouble codes from the ECM if you have any (shown by the "check engine" light). Pre-OBD-II vehicles can be retrieved using the instructions stickied at the top of the Toyota forum. OBD-II (1996 and some 95's...all 3rd gen Camrys with V6 are OBD-II) use a code scanner available at auto parts stores. Check the emissions label stuck to the hood or radiator crossbeam for your version.

I'll agree with Shorod on the IAC...they're pretty much set and forget, and they're auto-setting on install. Having to mess with that means something else is wrong that you are trying to compensate for. If you think that it is a clogged cat then disconnect the down pipe and see if the problem goes away (guessing you have the 4-cyl, 5S-FE engine)...there are three bolts you undo right in front of the engine between the exhaust manifold and down pipe, loosen them good to allow exhaust to escape and see if the engine idles better.

Second, yes, 15 years is alot of time for vacuum lines to crack and deteriorate so check them for breaks with some carb cleaner directed at them around the throttle body. Any change in rpm or stalling pinpoints where the leak is. Personally, my '92s were still pliable, but have been changing them out anyways when I can.

Third, check for proper fuel pressure. A clogged fuel filter, faulty fuel pressure regulator, or dying fuel pump can cause poor running and idling. Do you smell fuel in the exhaust?

Fourth, check your spark plugs for abnormal deposits. Are they golden or tan? Whitish? Black and sooty? Eroded or worn? "Reading" the plugs can often show an underlying problem.

Hope this helps!

it only stalled once or twice before i finally connected the flex pipe back on so i thought it was an exaust issue. thanks for the info that might fix this.

Any muffler shop can do a catalytic converter test for free.