When rpm's go up the car acts like it is struggling to speed up

While I was driving a 2006 Mazda 5 touring on the freeway,
I attempted to accelerate while going up a small incline, as
I pressed the gas and the rpm's began to increase, the car
lost power and I could no longer accelerate, as I pressed
the gas pedal the rpm's would not go past 3 rpm's or the
engine would struggle and act like it was going to stall out
or die. I could only go 5 to 10 mph, sometimes I could get
going faster but I had to ress on the gas a little bit and then
let off and repeat several times. I replaced the fuel pump
and filter but when you give it gas while in park or driving it
sounds like it's getting either to much air or not enough air.
While my dad was pressing on the gas and the rpm's was
around 3 or more, I could feel alot of hot air escaping from
the engine right where the air filter connects. What is the
solution to fix this? What would cause this sudden loss of
power and keep me from being to accelerate beyond 10
miles per hour or a little more. Please help