this is weird ok,I usually stay off the freeway if I can,but in So-Cal its nearly impossible,my problem is when i'm going on a straight flat freeway the car has good power,but if the freeway is going uphill my car nearly dies,i'll be going 75 before the incline and half way uphill i'm at 50 at WOT and the car shakes!anybody know what is causing this?Thanks

 

Have the exhaust checked for restrictions.