Freeride, what are you using to gauge 60MPH?
If it is the speedometer, have you verified its accuracy?
My 83 will do zero to what the speedo says is 60 in about 14 seconds, BUT my speedo reads 5 over actual speed.
Real 0-60 time is 17+

X2 on the check in both directions. Judging flat by eye is not as easy as most people think it is. I've done a fair amount of earth moving with diesels that do 0-6 in 12 seconds, and until you've busted out the transit, can't be sure it flat.