my 90 tt 108k miles,is misfiring then idoling you watch the tech moving up and down approx. 200 rpm, but when you give it gas it runs smooth, it does the same thing then I'm driving at lower speeds and as soon as I lay on the gas it runs fine. I replaced all the injectors @ 90k, sparks plugs at 82k. the car has been sitting outdoors in the weather, the past 2 weeks has been very rainy and humid. what should I check?