I have a 1991 Nissan D21 Hardbody. It doesn't pull a hill very well. It loses speed very rapidly and I sometimes have to drop down to 3rd gear on a highway just to make it up.
It also doesn't have a very high top speed. It gets up to about 55 without a problem, but after that it really struggles. I have only ever been able to get up to about 70. I'm not sure if this is normal for this truck or not.
Would a tune up help with this problem? Or what else could I do?