Scary Whirring Noise!
 

i got my car running smoother today i reaplaced all the gaskets and suddenly i started her up to get the no idle problem fixed and whenever i let of the throttle it makes this loud whirring whistle noise. sounds like the squealing noise of belts . so i tightend the alternator belt ( only on on the car now) and it went away but then came back , but the sound is coming from the back of the throttle body (where the cable connects to the pully...it scary sounding and it only happens when i let off the gas

A vacuum leak on the manifold can whistle pretty loud...

i took both the UIM and the LIM off today and checked all of the vacuum nipples and i had them all capped off....and any ideal why my car wont idle...i set the idle high and the car still dies.. i checked the timing and its dead on...(87 s4 NA)but when i let off the gas it dies..... 2 days ago i had it idleing at like 2k and it ran like crap but now it runs smooth but i have to keep it alive

Some of those lines you capped off might actually help you keep an idle better if they were connected properly. If you still have the problem after restoring the original configuration I'd be betting a vacuum leak, too.

also, make sure both surfaces where the intake manifolds meet eachother and meet the block are completely clean and free of all old gasket and debris. also, make sure you tighten all bolts in their correct order and to the torque specs

i cleaned the mating surfaces befor the install.....im waiting on a block off kit to come in i dont care about a good idle i juss want the car to stay on ....

i didnt have any problems like this befor and ive taken off and cleaned and redone the mani's befor many a time and never this problem.. i decided to do the rats nest removal and TB coolant bypass at diff times...

You can use a NON - LIT propane plumber's torch to find vacuum leaks. Just listen for the idle to change.

but it wont idle....it wont stay on unless i hold it at 3k .