Cold air at a stop

Ok so first of let me start by saying this is my first isuzu and so far im rather impressed. i have a 97 isuszu rodeo 2wd ls with the 3.2l v6 motor and 99900 on it. i too had the similar cel and abs lights come on but after hooking the car to a scanner i discovered theres more to this car than i originally thought. all i can say is thank god for snap on and their abs scan chip, turns out its the speed sensor and that is being replaced this week along with a whole new suspension. Now for my issue at hand, the truck runs great no idle issues no stalling sputtering or anything of the sort but it does burn alot of gas(any ideas?) and for some strange reason when i have the heater running and i come to stop at a light the air suddenly turns cold until i take off again. I cant imagine that being the thermostat but ill try it just to see. a little fyi the truck does heat up at idle for some reason but not on ever occasion. i would say 3/10 times the needle jumps up but then coasts its way back down upon acceleration. im hoping someone in here is knowledgable enough to help me sort out this problem. i live in buffalo, ny and the winters are pretty bad up here so all the heat i can get is essential. thanks in advance!!!

This sure sounds like a bad thermostat. Pretty common issue. T-stats are real easy to change on the 1993-1997 3.2L as well. Try to stick with a genuine OEM t-stat. I've had bad luck with a/m and cheaper parts stores t-stats.
G/luck!
Joel

so after flushing out the entire cooling system and putting in a new t-stat im still having this same issue...the engine temp gets hot when at idle or at a stoplight and yet the heat turns ice cold till the truck gets moving again...anyone else have any other ideas please help and thank you in advance.

Plugged radiator?

edit:

I just read this recent trend that points to the rad too:

http://www.automotiveforums.com/vbulletin/showthread.php?t=370547