Couple of quirks

Hey guys, I have a 94 Z28. Whenever I turn my heater on it blows fine, but its not that hot. It feels like some cold air is mixing in with the warm air. What would cause this?

Also, sometimes when the engine is under load ( like driving up a hill), the engine feels like it is hesitating. When I give it wide open throttle, it seems to go away a little. I thought maybe new plugs need to be installed. Any suggestions? Thanks :)

well, the heater problem sounds like a bad temperature door actuator, or at least bad seals around it.

as far as the hesitating, have you tried running it for codes???

could be bad spark, bad fuel or bad air. has it recently had a tune up, air filters, fuel filter, all that fun stuff?

is it auto or manual?

Its an automatic. I havent given it the tune-up yet, but I plan on doing it soon.