What kind of radio do you have?

With dual rates you have the ability to have different amount of throw or travel on the particular control surface (elevator, ailerons, rudder). Per your post, you say you're not getting enough travel/deflection on the elevator to provide the necessary pitch to lift the nose at the proper speed to provide lift. The problem can be one of three things maybe. I would first look at your elevator and make sure it's not binding in any way and allowed to move freely up and down. Then look EPA (end point adjustment), on your radio. If your EPA settings on your transmitter are set to the max you might want to consider moving the control rod closer to the surface on the control horn. This applies to the ailerons as well, which will provide more deflection and a quicker roll rate.

Now with dual rates. You can have one rate(low) set to where the deflection is minimal say 80-90% of EPA, then you can program 100-110% of travel to the surface to serve as the high rate which is enaged by flipping the D/R switch on your transmitter.

Hope this helps and didn't confuse you. Look at your transmitter manual, it should give a good explanation of dual rates and how to set them up.

good luck and welcome back,