hollow sound

i have a 91 turbo talon
#1 when my cars rpm's are below 3000 it sounds kinda loud and hollow
#2 when cold the idle used to jump so i took it in and now my rpms are constantly at 2-3000 rpm when cold or warm and ive tightend that bold on my trottle body down
#3 last one i think.. when the rpms are above 4500 there is a loud noise and kind of a vibration

so i donno what too do and i dont feel like spends a ton of money for people too rip me off so thanks for the help

Explain the noise at 4500 RPMS.... and by vibrations do you mean like your car is heating a wall? or just that your car shakes alot, It could be that your motor mounts are shot to tell. But it would be more help if you could describe the noise though, don't be worried, usually in cold weather our 1g's kinda suck at start up.

it sounds like the engine is trying way to hard and the noise is kind of like something is loose but its drawing my power away does that help?