I just replaced the throttle position sensor in my truck and now in park it idles at 1500rpm instead of 700rpm

The 2007 Ford Explorer Sport Trac does not utilize the once-common idle air control (IAC) valve. Instead, an electronic throttle body is used. An electronic throttle body is a traditional butterfly throttle valve that has an electric motor attached to it. Instead of opening via a throttle cable, it is opened by the powertrain control module (PCM) when the accelerator pedal position (APP) sensor (which is the gas pedal) is pressed. The PCM also adjusted the throttle blade position in order to achieve proper idle speeds. Often times idle problems with this type of electronic throttle body are caused by carbon buildup around the throttle plate, in the bore of the throttle body. In fact, this is such a common problem with this particular vehicle that Ford released technical service bulletin (TSB) #12-7-4 to address the RPM fluctuation and hard start symptoms and advises to clean the throttle body. Alternatively, the throttle body can and may need to be replaced. You can read more about this issue here: https://www.yourmechanic.com/article/how-to-replace-a-throttle-body-due-to-carbon-build-up-on-most-vehicles-by-ty-thompson

A new mechanic, definitely!

Try checking Angie's List for reputable mechanics near you.

check your throttle position sensor and your maf sensor.

have exhaust back pressure tested. maybe the catalytic converter is restricted/ almost plugged. Also check your vacuum hoses for leaks.

code po172 is your bank 1 o2 sensor and code po121 is your throttle posit sensor that controls your RPMs .code po102 is your maf -mass air flow sensor. and code 01172 is a throw in code from the others cause problem. you need a o2 sensor and mass air flow sensor and throttle position senor

could be a (tps)throttle position sensor also look at (maf)mass airflow sensor/(map)manifold absolute pressure sensor.(iac)idle air control valve...or and a bigger fix a leaking intake manifold gasket but will usually stall when stoping or idleing down.hope this helps so many possibilities but i hope this helps.please rate my answer,and thankyou for using fix ya.

It could be both. You can test both with an ohmmeter. Missfire is usually do to faulty plug wire or bad plug. If not idling correct, then the idle control valve or 02 sensor is faulty. If missfiring or popping during acceleration would indicate faulty throttle position sensor.

Your throttle body likely needs cleaning.

Take the intake hose off and using throttle body cleaner or brake cleaner, spray a rag and use our fingers to clean the gunk off the throttle plate and the contacting area of the inside of the throttle body.

Some times the E.G.R. will stick half open. This will make the engine surge or have high idle. Try replaceing the E.G.R. located under the upper intake. Do not go with after market E.G.R. The spring in them are to powrefil and the E.G.R. wil not open. Also try replaceing the O2 sensors. This could give the engine more fuel thus a higher idle. Some vehicles the T.P.S. can be ajusted, do some checking to see if yours is adjustable.

Please contact me if your problem presists.
Thanks, Charlie

try replacing your map sensor or your throttle position sensor.