2002 Crn Vic-Will start but won't stay running-HELP!

My 2002 Crn Vic. starts up fine, but won't stay running unless you keep your foot on the gas pedal and rev it up, until it begins to idle on it's own.....sometimes taking up to 30 minutes. Once it begins to idle on it's own though, it runs fine. But if you turn it off, you have to go through this process all over again. It also has quit on me while driving (when I am accelerating suddenly, such as when merging onto a highway ramp.) It has thrown codes for EGR Valve, EGR Sensor, & Misfires. I have replaced the EGR Sensor, my mechanic said it didn't need EGR Valve. Also, just replaced # 5 Ignition Coil. BUT, when mechanic took it for test drive after repair, he said it quit on them while driving, and that it MAY be the Idle Air Control. HELP! What is the real problem with this car...I can't keep sinking money into repairs that are not solving the problem!!

Your mechanic is on the right track. Needing to hold the gas until it will idle by itself, and having to do it all over again every time you restart, is the classic symptom of a sticking idle air control valve or a dirty throttle body. The IAC is the small valve bolted to the throttle body at the top of the engine. It lets air around the closed throttle plate so the engine can idle with your foot off the gas. If it's sticking, or the passages are caked with carbon, the engine can't get enough air to idle and stalls unless you crack the throttle yourself.

The cheap way to start:
- Clean the throttle body bore and the small bypass passages around the throttle plate with throttle body cleaner. Then pull the IAC and clean it too.
- If cleaning doesn't fix it, replace the IAC. These do wear out, and cleaning doesn't always bring one back. Buy a Motorcraft one. Some owners have had cheap aftermarket IACs make the idle worse.
- Look for vacuum leaks: cracked hoses, a split intake tube between the air filter and throttle body, or loose PCV hoses. Any of these can cause the same stalling.

The EGR codes may be part of it, since carbon in the EGR passages also causes rough idle and stalling. Ask the shop for the exact code numbers (like P0401) and post them here. Those tell us much more than 'EGR code'. Also, if the misfire code was for cylinder 5 and the new coil cleared it, that part is done. If a misfire code comes back, write down which cylinder.

The stalling when you accelerate hard to merge is a separate symptom, and it's dangerous in traffic. Once the idle is fixed, if it still stumbles under hard throttle, have the fuel pressure checked next.

Dana