98 Weak Key Fob

Can anyone tell me how I can get more range with the remote key fob? I
have already replaced the batteries in both fobs and I still have to
get within a few feet of the truck in order to lock or unlock the
doors.

Another problem, the fob will not unlock the doors if the engine is
running. A real bummer on these frosty mornings.

Thanks for any suggestion you can pass my way.