hey all, thanks for any input you can give me.
I have a 91 blazer that i got real cheap (500 bucks), so i got more than i paid for it.
Anywho- I have an extremely high idle when i first start it when its cold.
and i have a intake manifold gasket leak
this truck has **** poor heat and i live in New England where we get 10 months of winter LOL.
4.3 throttle body 4DR 4x4

 

I would first check the TBI base gasket. These are known to go bad, causing a high idle.

About your heat issue, is the system up to the proper coolant level? If so, then it is very likely that you have a restricted heater core. Do you get any heat out at all? Are both of the heater hoses the same temperature?

 

How does the dash gauge read...possible thermostat issue if gauge works and the vehicle only gets to 150-170 degrees.(or less) Just a thought. JP

 

The coolant level is good even though i have a small leak @ the thermostat housing (i lose about 2 cups of antifreeze a week).A new thermostat, both hoses are roughly same temp.
My temp gauge doesn't work, another prob.
I do get heat but nowhere near as much as my 94 Jimmy puts out.

 

If coolant level is good. T'stat is good..as Kyle said-I'd be super suspicious(if fan is working and blowing-if dash interior panel is 'mode' switching) of the heater core being partially plugged. The way I go about it is with my handy dandy LED laser pointer thermometer. Got it at Graingers-see em all over the place and I think they can be had for $50ish-hey ask Santa. They are super handy and eliminate all guess work as to how hot/warm is it. Measure both hoses where they go thru the firewall on the fire wall side. Let us know the readings. Had one the other day 130ish degrees in not even 100 out...flushed core-good to go. In fact did my wifes Blazer-three weeks ago or so and now she has to turn it down on her way to and from work! There's nothing like a happy/warm wife. JP

 

this mode switching I know that there are vacuum lines that attach to the controls would a vacuumleak cause problems that would cut heat output i do get geat at floor and defrost just not that great.
i do hear "hissing" behind the dash
vacuum lines are attached where they belong on the controls
As for a warm/happy wife, when I finally change the tranny in her 94 Jimmy she'll be happy so I"ll be happy

 

Yes, the HVAC system is all vacuum controlled. A vacuum leak will result in the HVAC system defaulting to the floor/defrost as you have described. The mode door would also go to its neutral position which could cut heat output. Looks like you have a vacuum leak that needs to be found.