Insufficient coolant , trapped air in the cooling system might not have enough coolant to full fill the heater core..
The hot coolant flows from the engine to the heater core through the "inlet" hose. After circulating through the core, the coolant returns to the water pump through the "outlet" or "return" hose. Both the inlet and outlet return hoses should feel hot when the engine is at normal operating temperature and the heater is on.

1. If the both heater core hoses were cooled, then this vehicle might have an insufficient coolant in the cooling system.
2. If the heater core inlet hose is hot and the outlet hose is cool, the heater core might be clogged.

does it kinda sound like marbles in a wooden box being shook?? blower motors go out alot, and the fan blades hit some areas around them. It usually gets worse and worse. with the car running, turn off heat/cooing system and see if it stops. blower motors seem to get worse in the cold weather, bearings
get dry after years of use, and just have to change it out, no repair here to do. not hard at all.

This can be wiring (a shorted wire, open wire, or wire with high resistance between the engine controller and the instrument panel), a controller fault, or an instrument panel cluster fault. Have someone pull codes for you, and that will help you zero in. - Lew Carite at carite.com

Please rewrite this with more explicit detail about what you mean by "heater barely blow". You could mean the force of the air (blower speed) or you could mean the temperature of the air and are you saying that in seconds that you temperature gauge drops from 225 F to 100 F ?

Possible causes:

The new fuel pump may have come with a faulty leveler unit.
If you replaced just the motor, the connection may have gotten damaged.
The plug to the pump is not seated properly or at all.
The leveler got damaged while getting re-installed.

Unfortunately there is no easy fix to this without pulling the pump again.

Ben @ MechanicsCentral.com

Yes what about it?

Were looking at 150-200 for the parts, for the labor, you have to use the find a shop button to make a couple of calls or use the negotiator tab and they will call for you.

See this FIG : Fuel pump and sending unit module assembly
http://www.autozone.com/.../...rGuideContent.jsp

The fuel sending float unit may be stuck and it didn't sent the reading signal to the fuel gauge.

"The mechanics there say its my interlock and the interlock place says its not that." - What did the interlock place say the problem was? They just cant say "its not that!" without telling you what the problem really is?

Driver side top of engine. Toward the back, just behind the throttle body. It's electronic, has a connector plugged into the top of it.

Talk to us more about this and what led up to.

Are you referring to the plastic housing on the driver side of the engine cylinder head that has two hoses and a sensor attached to it? If so, see that the brand that you install is genuine ACDELCO - part # is 24575259 and make certain that you do not have an overheating engine of course. I assume that if it was overheating you would have said that.