I used to really stuggle with the problem you described. How I hated those dreams of running away and not being able to will my legs to move! Or I'd try to yell, and nothing would come out. So frusterating!

I almost never have this happen to me anymore. I made it get better by doing a few things.

1. I turned around and conftonted what/whoever was chasing me. I asked them why they were chasing me and told them to stop. I did this over and over, until I no longer felt afraid during these dreams.

2. I got more exercize and better sleep. This helped the feelings of sluggishness in my dreams.

3. I talked to someone about the waking life problems I thought were the cause of the bad dreams.

4. I seriously persued lucid dreaming -- getting lucid as often as possible, and as "clear headed" as possible.

I know that this is often a complex issue and can be hard to deal with. Often there is no "quick" fix. If you want to talk more about how I got past this kind of dream you can PM me anytime.