About 3/4 of the way through last winter, my heat went from hot to barely warm. This winter I have very little heat.

A/C works fine..all controls work fine (except for 4x4 which I'll post next).

Suggestions greatly appreciated....

LESTER
Can you elaborate where the heater core and firewall are located?

I think your thermostat is stuck.
Buy a new one and change it.
If this doesn't work you may want to flush the heater core.
Buy a can of radiator flush and follow the directions.

Do not use pressurized air to blow out the core, as any more than 15 psi will blow up your core.

That what I did on my '99 S10 (V6 4.3 L) two days ago.I pulled two heater hoses from heater core,you can see them sticking out from firewall.Put lot of rags on the top of distributor cap(not to get it wet) and run shop air trough heater core.O boy!Lot of s***t come out of there!Kept running air for a minute,then put hoses back,refiled with coolant and (OH GOD!) I've got HOT-HOT air again from my vents.YAHOOOOOOOOOO!