I changed my IAC valve on my 2004 ford taurus dohc, and now the rpms sit between 2000 and 2500. I checked it with a scanner and it gave me the code p0511....How can i fix this?

Have you tried resetting the code yourself with a scanner? Have you measured the voltage output from the alternator while idling?

the gasket under the iac

Possible bad Idle Air Control valve. (same issue with my mustang.)
Replaced the IAC and everything smoothed out perfect.

it would usually be the tps (throttle positioning sensor) but you can also check the icv (idle control valve)

What engine? 3.0 OHV or 3.0 DOHC

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

I'm kinda guessing the "hose" you are "pinching" off is the air assist to your injectors as most IAC Valves don't have any hoses unless it's this type of system. Are you gettting any codes or is your check engine light on ? I would guess that you have a vacuum leak which would be the most common cause of this kind of thing. You can check for one by spraying some carb/thottle body cleaner on your vacuum lines and aound the intake manifold, if the idle changes as you are spraying, you have located the general area of the vacuum leaks. If you are haveing problems in the IAC valve your check engine light should come on and pulling the code(s) will help you to narrow down the problem. Comment here to let me know if you have the light on and if you are gettting any codes and what they are. This would help me to help you better. Below I gave you a description of how the system works to help you understand the system better. I would check for a vacuum leak first. I know this wasn't a whole lot of help but I hope it helped you a little bit anyhow.

P1506 Idle Air Control
Overspeed Error

IAC Valve--Bad
Vacuum Leaks
IAC Stuck Open
Failed EAVP System

Disconnect the valve--if little
or no change in RPM,then
Valve is stuck or bad

There is a large vac line coming straight down from the throttle body that goes to the PCV system. See if it has a hole in it. It is likely sucking air.

check tps senser

I figured out what was going on. supposedly on ford rangers the Idle Air Control Valve (IAC Valve) goes bad. i got a trouble code looked it up and sure enough it is the IAC Valve. Under 100 bucks for the part