Well.... I'm stumped and could use the help
 

I just spent the last two days working on my truck, checking the lines, replacing a couple parts, and researching trying to fix her. But nothing seems to help.

Research around and found a few that sounded like the problem I am having and tried what was recommended, but nothing seems to make any real changes. So here it goes, I'm tired of throwing money away with no results

Truck started to idle and run real rough, loss of power, loss of throttle response, feels like I'm towing a fully load trailer behind me while driving. She sounds like she is idling real high ( almost what it would sound like when it is revved up to 5000 RPM's ), and whistling, but the RMP shows she is only idling at 1200 and I have her set to 800-1000 RPM. While driving if I go over 2100 RPMs sounds like the engine is going to blow. Worst part about this is it's not even throwing any codes, I can force a code to be thrown, and yes the check engine light works.

I've checked, cleaned and even replace the Idle Air Control (IAC) valve. Replaced after covering the ports and noticed it wasn't opening when the truck would start and could feel it trying to engage. The symptoms reduced a little after replacing.

It was recommended to replace the Throttle Position Sensor. No change.

Truck will idle and sound perfect once the IAC valve is unplugged and still attached, but once you give her any gas the over revving and whistling sounds return for a few seconds but goes away. Also with it unplugged the truck RMP gauge shows her idling between 800 and 1000.

Any ideas????

you probably have a nearly plugged up catalytic converter or 2

Seems like a bad vacuum line somewhere.JMHO.

good point , could also be the large vacuum tube to the brake vacuum booster

those elbows are notorious from cracking by the high manifold heat

It turned out being the fan clutch. Thanks guys for the advice.