95 Park Ave Ultra, rough coughing idle

[95park]

My 95 Park Ave Ultra with 106K miles has recently started to idle rough. Almost like she is having a hard time breathing at low rpm violently shaking or going off when I start her up.

At high rpm or driving on highway is fine and engine sounds great. In fact, just installed new battery, tires, back rotors and recent oil change...

I was thinking its because the car is getting old but just doesn't sound right. She was fine last week.

Help...!

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[eliotness]

I have a '93 Park Ave, 148,000 miles and the same problem. Car stalls at low rpm, mostly when engine is cold. Rough idle as well. No problem on higher rpm (>2000) . Tried high-test gas, fuel line water remover without improvement. This happens mostly when the tank is less than 1/4 full. I suspect this might be a clogged fuel filter.

[parkavenuechrome]

Sounds like a Dirty or Bad IAC valve or IDLE AIR CONTROL VALVE.. they get dirty and stick and or fail.. Try cleaning it and replace as necessary.

[eliotness]

I replaced the valve- the old one was really dirty. No more stalling !!!! Thanks for the tip !

Idle is still somewhat rought though....maybe time to replace the fuel injectors ?

[parkavenuechrome]

Run a bottle of k100G thru the fuel.. Get on the highway and blast it to redline and clean out the motor.. you probably have some carbon depostits on the piston heads from the IAC going bad. Also change the O2 sensor. After the rich mixture the sensor is probably clogged up with junk.

[agamino]

Where is the IAC valve located on the Ultra? I have a 1992 PA Ultra with a similar problem.

[jwalk1a]

I agree with park-ave-chrome. A bad O2 sensor, aka Oxygen Sensor, would account for the rough idle and also poor gas mileage. It's cheap enough and easy to get to if you want to replace it yourself. You can borrow the special socket you'll need from a parts store chain for a refundable deposit.

-Jon