Idle drops low then tahoe dies out.

[Awh8d]

I have 04 tahoe, I start my tahoe and instantly everything sounds different. The idle is really low, my exhaust isn't loud like usual. And it feels like it's running out of gas.,i let it idle for awhile and it goes up and down. If I rev the motor, my oil gauge goes up and when released it down.if I turn on my a/c the idle drops more low then if I put it into gear it dies. The a/c will blow warm air but when I rev it it will come cool. If I turn off the a/c and put it into gear it's still low but doesn't die out.then the most unusual thing is my positive terminal was really hot. I changed my battery now the wire isn't hot.but my idle isn't the same.anyone had these symptoms and found out the problem?

 

[rockenthebowtie]

idle drops low then tahoe dies out

Have you tried cleaning out the throttle body.. start there if that doesn't work check for for DTCs may have p0171 and or p0174 fuel trim system lean banks 1 & 2 if so check upper intake manifold gasket vacuum leaks.. if ok check fuel pressure and or a plugged exhaust