i bought this car 2nd hand (75000kms)over 2years no problem but now its 135000kms every time i drive my car 120kph for 30mins i get this shift shock or loss of power(im not sure between the two) about 6 seconds.it will disappear and car goes on no problem. it also(sometimes) shift shock(a bit) as well once i press the gas pedal after the traffic lights goes green and the rpm increases 20-30% than normal once the car starts rolling. me and my mechanic had checked the air and fuel filters-both ok and clean, plug a computer scanner(mitsubishi scanner computer) to detect any problems via computer and sensors-no fault found, replaced new spark plugs. just bought new harness/coil but haven't tried driving the car more than 30mins and at the moment its fine. is there any parts that causes these problems??? everytime we clean or check somethig(spark plug, filters and harness) it tends to go back(shift shock or loss of power) after 2 days same driving speed and duration of journey..PLEASE HELP THANKS