Trouble Code: P0455= EVAP System Gross Leak (0.080") Detected

Possible Causes:

Fuel tank cap is loose or missing
EVAP purge control vacuum line is loose or not connected
EVAP purge solenoid is damaged or has failed
EVAP emission canister clogged or restricted

Sometimes you can correct this code by simply unscrewing the fuel cap and reinstalling it correctly - to see if the code goes away.

I would replace the gas cap, erase the code with a code reader and see if it solves it because the cap is the cause most times and the cap is like 6 bucks and is free of labor to replace.

See this http://www.automd.com/shops/

Give them a call, let them know their shops are recommended by AutoMD.com

Check with various online stores and see how much they charge, AutoMD is okay but you can also check with http://4wheelonline.com/Cold_Air_Intakes.151438

your probably looking around 600-700

You have a bad engine mount. It will be the mechanic's job to determine which one and then replace it. I do not know the cost because I do not know which one is bad. probability here is almost 100%.

Having same problem right now with my Buick Skylark Custom 2.3 liter
I believe it is either the O2 sensor or the Throttle Position Sensor. Most likely cause for you as well!! Best of luck to the both of us :)
Testing our sensors tomorrow

Or I guess nevermind sorry mis-read thought you said it vibrated when in P or N.

Best of luck to you anyhow!

correction *EGR

You have a bad crank sensor. It is behind the harmonic balancer.

Plug in a code reader and see what fault codes are stored. That is the first step toward repairing it yourself. A code reader can be purchased from Amazon for as little as $21.00 and it takes two minutes to read the codes.

First step - have the check engine light or stored fault codes scanned - for free - at any local auto parts store; Advance Auto, Auto Zone, NAPA. Then, post a reply as 'add answer' with the specific fault code for more assistance.

Possible Causes of Engine Hesitation or Stumble:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

Dup...............

Read fault codes and repost with the code numbers. the mass air flow sensor is a high probability here.

Read fault codes and post the codes here. if no codes are there after checking, state that.

When the engine is first started, and rpm is above 400 rpm, the system goes into 'Open Loop' operation. In 'Open Loop', the ECM will ignore the signal from the Oxygen (O2) sensor and calculate the air/fuel ratio based on inputs from the coolant and MAF sensors, but mostly from a pre-programmed table in the memcal.

The system will stay in 'Open Loop' until the following conditions are met:

1. The O2 sensor has varying voltage output, showing that it is hot enough to operate properly. (This depends on temperature)
2. The coolant sensor is above a specified temperature about 40oC/104oF.
3. A specific amount of time has elapsed after starting the engine.

The specific values for the above conditions vary with different engines and are stored in the mem-cal. When these conditions are met, the system goes into 'Closed Loop' operation. In 'Closed Loop', the ECM will calculate the air/fuel ratio (injector on-time) based on the various sensors but mainly the O2 sensor. This allows the air/fuel ratio to stay very close to 14.7:1.
Check the oxygen sensor and replace it as necessary.

A really good mechanic has to hear this. There is no way to even speculate about a cause.