I am having a "chugging" issue with my SUV 2006 Mercury Mountaineer.

I have a very similar issue with my GM car. I've been able to reduce the chugging little by little by finding and fixing tiny vacuum leaks. With my car it starts fine and runs fine for the first trip of the day. Then when I restart it it will start chugging and uses more gas to make it go. I'm almost positive that testing a MAP Sensor is part of a diagnosis using a good scan tool or code reader. I would go have it scanned if you can. You can do that for free at AutoZone or other auto parts stores. If you do solve the issue completely please let me know what was causing it. Thanks and good luck. Thanks and good luck

6 or 8 cylinder? Last tune up? Tell us when it does it, at road speed after it is in the highest gear under light throtte on slight incline? Taking off from a stop? Letting up on gas pedal and coasting? WHEN? Under what conditions? No check engine light has been on? Different ignition systems for 6-4.0 or 8-4.6 eng!