signs of bad intake manifold gaskets

[blacksambo]

I actually had a high pitch whistling and the rpms would go up and down and the motor would die when changing gears,so I replaced both upper and lower gaskets and it was fixed.

Sounds like the good old 171 code. The original gaskets were torqued to 18lbs. Five pounds too much. They are made of brittle plastic and crack letting too much air in to the intake area. I know it's a pain but change the devils. Your idle will immediately behave properly.