NEED HELP with Hesitation Problem

I have a 99 manual S-10 (69k miles), never had a problem... Recently after driving any distance and coming to a stop the truck doesn't seem to get enough gas to move forward. Almost like I had the emergency brake on. If I turn the car off and then on it runs fine. Checked the fluids... my last oil change it was too cold to do myself so I got it done at a place where they said they checked all the fluids... well needless to say the coolant was very VERY low... filled it back up but I am still having the same problem and now the Check engine light is on... I think maybe I lost a vacuum in the radiator or the fuel pump is acting up... Need some help, please...

I think I am going to flush the radiator and replace the thermometer (perhaps it was damaged due to the low level). If that doesn't work I will have to replace the O2 sensor. Anybody have any advice or comment on that chosen path?

Keep an eye on my post for "S-10 Hesitation." We have very similar issues but I have not found an answer yet.