Well as you know I have had that stalling problem. I haven't dared taken it very far from the house because of that problem that I can't seem to figure out what it is. Checked the spark plugs and they need to be changed a few thousand miles ago. So I just got my intake put together everything was ordered before the stalling problem. Man it sounds good and has a bit more power. So I took it on a stretch of road next to the house to check acceleration it was nice did about 1/8 mile and I smell coolant from the vents and then I hear a splash out of the center vent narrowly missing my foot which was good because I was wearing sandals. Turned around and went home. So yeah this sucks. Guess I will need a new heater core which will be loads of fun to remove and replace. Looks like I will need to get my Blazer back on insurance to drive around since that is running good but had a slight pulling randomly at high speeds but I think it was the loose caliper but its tightened up so it should be fine now. Any other things I should replace while I'm at it now that the Bonneville is out of commission for awhile.

I'm sorry to hear about your troubles.
A heater core swap isn't too bad. The factory clamps are the worst part. It is a lot easier to replace the original spring clamps with screw clamps.
Search my old posts, I did a thorough one when I changed my heater core.