I have no heat. The truck gets up to about 192 then settles to 188 and back to 192 again. The blower is working and the air coming out is only about 50-60. Where should i start looking. There is no air in the system and the other day when driving along i noticed a slight haze, almost looked like smoke but no smell coming from one of the vents. Thanks in advance.

 

Try this, take the heater hoses off and run a garden hose throught each hose full pressure to blow out any buildup that might be in there hook them up and see if that helps

 

Please keep in mind that your cooling system max pressure in use is somewhere in the vicinity of 15 psi, and your garden hose pressure is closer to 60 psi.
If water flows freely through the heater core, look into blend door actuation. Check for vacuum leaks, since that is what moves the blend door.

 

According to Dodge (http://dodgeram.info/tsb/1994/07-07-94.htm) the engine temp fluctuation is normal. Uhhh...... I don't think so. May be normal to them but I can't stand that. I drilled a 1/16" hole in the flange of the thermostat. One hole does the trick on my truck, some guys use two. Anyways, do that and the temp stays consistent.
The cab heat issue is usually the blend door. Not sure exactly how to check that without going through a whole bunch of work. Like grider pirate said, check for vacuum line leaks.
I know a guy that filled his cooling system with water and poured a couple jugs of CLR into it and ran it like that for 3 days. When he drained it out, it was all brown slime. A couple flushes later he had cab heat again.

 

I agree with checking the blend door.......but it's not vacuum actuated, it's electrically actuated. There is a small electric motor in the bottom of the HVAC case in the passenger-side footwell. It's a real pain, but it can be removed and checked without removing the entire HVAC case.

 

No kidding! I would do that if it wasn't winter. Guess I will just pull the heater core using the easy method.

 

If you suspect heater core and want to save some time and play with fire, disconnect your heater lines to the core and fill it with muriatic acid. Let that sit for 2-3 minuites and flush it out. Hook up rubber lines to the heater core lines and BE CAREFULL with this stuff. Wear chemical gloves, don't breath it and don't get a drip on anything! It eats everything - fast!
The biggest risk here is if the walls on the core are corroded thin, it may leak after. Like I said, kinda playing with fire.
I've done it a few times and gotten away with it, just know the consequences.
Figured I'd throw that in there if you're willing to pull the core anyways.