I have a volvo 240 Dl sedan, its a stick and came with the clock instead of a tach. after installing an aftremarket tach, i noticed the idle was between 900-1000, (The idiling is very loud). well i wanted it normal so i checked to make sure all hoses on throttle body were on. After doing so i started up and voila my idle was between 700-750. after letting the car sit for a day without starting it up i started it up today and the idle is back to 1000. my car has 218,000 km on it i would like it the idle low again, i checked all hoses and they were the same, i even did the same procedure as before but nothing, i let the car heat up but the idle stayed the constant 1000, please help!!!