hi i have  a sonata 1994 model 2.00 cdi with 100k miles on clock

ye cars been really good up till now

3mths ago it started with no idle but i can live with that by just stepping up on the gas to bring the engin rev up

more worrying lately its got a battery drain problem(no warning lights on dashboard=normal lights) = have had the alternator checked out at an auto elec  place who says its perfect=not wrong so i guessed it must be the battery

fitted a new battery but the problems still there it just drains out after 4 days or about 100miles

its all factory torqued and no ones played with it yet, am now lost to see what the problem is

any help and ideas please

since posting this i have now got a meter to tell me if the charging current is on or not. well it charges purfect when engine is cold and as the engine heats up say in 2 miles the charge lighton the gadget  drops out and drains the battery. let the engine cool down and the whole thing starts again ie charging when cold and when hot in 3 miles it drains

any replies would help