bro, i'm about to have a heart attack just from reading what you wrote. relax.
if it runs better the higher you rev, its likely a vacuum leak but obviously not always. it doesn't take much. for example a while back i bought a brand new intake bellow. before that my car idle was perfect, the tachometer was glued. i replaced the bellow, my old one was in 'fine' condition, 1 crack the width of a hair almost impossible to notice. with the new bellow the car just died. fixing one vacuum leak caused another one further forward to play a bigger role. if you're using brand new parts most likely you plugged something in wrong. if not, inspect them thoroughly, use ducktape or rtv to cover cracks as temporary fix to narrow down the cause. use spray to find leaks. look up "mess under the intake" mod. try to meet up with a m42 owner in your area!
there was a thread about a pro way to find leaks, forgot what it was...
Topic: She WOnt Hold an IDLE....ANY HELP! (Read 2813 times)