I have a 99 ranger and just replaced the radiator, thermostat, water pump, and had my heads checked. It cost $1100 and they had the truck for a month. It was running fine when i got it back but it was not warming up to the correct temperature. It is blowing hot air. Now it is running rough, check engine light is on and its showing code P0171. I don't work on trucks. I would just like some honest feedback about what to do. Thanks

 

Most likely a vacuum leak from a dislodged or cracked hose.
Start the engine and put your hand on all the (small) vacuum hoses going to the intake.
Wiggle them / feel them to see if the idle rpms change.

https://www.obd-codes.com/p0171

 

 

I think you may have been ripped off. $1100 sounds like way too high for radiator and water pump. Don’t know what it means to have the heads checked but that work should not have taken a month.

Looking at YouTube, a good mechanic can troubleshoot heads with a scanner and follow up with compression tests and leakdown tests. Worst case scenario they inspect cams, spring and rockers with the valve cover off. None of this should take longer than a day or two.

I have seen people using a small propane tank (unlit) to find leaks. The vacuum leak sucks in the propane at the leaking area and you will hear the engine rpm pickup. Safer than using starter fluid.

When you say “blowing hot air” I’m assuming the AC is not working. Again a lot of good videos on how to troubleshoot on YouTube. If you are not looking to learn how to do things yourself find a better mechanic. See if there is a yard sale Facebook group in your area and ask for a recommendation for a good mechanic.

Good luck.