No stored codes or just no check engine light? Sorry have to ask, a lot of people think that the CEL comes on if ANY codes are stored and that's not true, MOST don't cause it to light up.
The bogging when the heat comes on is something I'm going to have to think about.... The first thing that comes to mind is that the heater is drawing more current than the alternator can provide... could also account for stalling. Check the voltage from the alternator and then while watching the meter have someone turn on the heat.
As for the stalling I'd start with checking that the ISCV (Idle Speed Control Valve) isn't clogged and test it; Then test the AFM; Test and calibrate the TPS; Check for vacuum leaks or openings in the intake piping.
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