Hi, I recently purchased a 85 k-5 with a 6.2 and 700r4. It's in excellent condition and runs and drives great. Driving around town seems fine but when I'm on the interstate and hit any kind of hill it needs to downshift (3.08s) and can barely hold 45 mph on larger hills. I'm ok if thats all it has but just want to know if it's somewhat normal. It also shoots out black smoke when I give it any kind of throttle. It runs extremly smooth and idles perfect. It's like a smoke show behind me on any sort of hill. I checked underneath and mufflers look like they are leaking oil. Is this sort of power and smoking normal? I will change fuel filter and air filter even though they look recent. I have done a search and think it could be the cdr valve or egr? When I remove the oil cap or dipstick when it is idleing I don't see any blowby. Any advice would be helpful.