i have an A4 1.8t 99 and recently my idle is fluxuating intermittently but it only seems to happen when my car is warmed up. i have already changed my coolant temp sensor and fixed some hoses that were slightly leaking.. i thought maybe i have an air pocket in the coolant system but there is no bleeder screw for these cars (so i think). when the idle starts to become irratic and start to feel like it will stall it will start reving above 2grand and then blow out smoke the tail pipe.im guessing to compensate for the low idle..does any1 have an ideas???