I have a 97 2.3 ranger that has started having some problems recently, It started with staring rough and sputtering a little when cold out, then it got to where it would stall when you shifted into gear unless it was warm or you gave it some gas at the same time as shifting. here recently it doesn't want to stay running at all unless you are giving it gas, at every red light or stop sign it stalls. when in motion it runs great. I just changed the spark plugs, air filter, fuel filter, and iac and fuel pump is less than 5 months old. took it to a family friend mechanic and he is completely stumped as to what I could be. it is throwing the following codes p0172, fuel system rich bank 1, p1121 tp sensor inconsistent with MAF, p1504 iac circuit malfunction, and there was another one for iac over speed that I can't remember the code for, I should also add I replaced PVC valve and grommet and repaired any vaccuum leaks I could find. another weird thing is it tries to run a little better if I pinch the vacuum hose coming from the bottom of the throttle body, I'm new to this so sorry if I didn't explain it well. I just can't figure out why it keeps flooding itself out, any ideas?? thank you in advance, I should also probably add I did adjust what I thought was the idle screw to turn the idle up a little bit and that helped for a little but now idle does not change when unplugging the iac, I did verify power at the iac plug.. I think... one side lit up the rest light

 

I would clean the throttle body and then make sure the IAC is working. I know you said it is new, but the code mentioned "the IAC circuit".. The computer is supposed to set the idle speed using the IAC, so your work with the screw should not have been necessary.