Mitsubishi Forum - Mitsubishi Enthusiast Forums - Mirage ES 2001 4 Cy 1.8L P401 EGR Problem

My Mitsubishi Mirage 2001 ES(Engine 4-1834 1.8 L) Auto Trans car dashboard display "Service EngineSoon" Message. At start I could feel some sort of jerky motion around 122K mileages. Received the Engine check code #302. Identified as misfiring inCyclinder-2. Tune up including Spark plugs, coil on plug boot (500021), TailorRes wires (8910), Valve cover GSKT set (VS50535R) replaced. The car was running OK. Within few days got newcode #401 EGR Flow Insufficient Detected. Switched to another mechanic. The car had been to shop 5 timesnow. The shop claims they cleanedthoroughly EGR valve passage, carbon deposits. In subsequent visits replacedthe EGR valve and sensor. After the repairs each time it will be Ok for fewdays to 1-2 weeks and again the check engine light will come-up. The mechanicsaid the voltage at sensors shows proper value but still the light comes-up.Since the battery is 5 years old we replaced with new battery. To our pleasant surprise for 3 weeks there wasno light. My wife thinks it happens few days after filling the gas. Anything couldpotentially be wrong with the gas tank cap? One theory is the pressure withinthe gas tank is not maintained OK due to cap not tightly secured? The car runs verygood for 12 years old; there is neither hesitation nor jerky ride nor gas smellnor smoke from tailpipes. We already sank over $600. Very frustrating to seethe design by car manufacturers. If a trained mechanic could not identify theroot cause of the problem from the code it sucks. I do not want to go to thedealer who will rip you off. Any mechanic shop who will fix the problem in NorthernVA area close to Manassas (ZIP 20155).

The car is running good other than "Check Engine Soon Sign". Any help is much appreciated. Thanks