1988 Ford Ranger 4x4 w/3"lift , shakes and jerks in 1st gear what would cause this?

I'm considering buying a 1988 Ford Ranger 4x4 w/3"lift and 15"tall
tires. It has 145,000 miles on a 2.9L V6,5-speed. The guy has owned it
since 1990 and installed the lift shortly after purchasing it.
In the test drive starting out in first gear the truck jerks/studders
a bit but smooths out and 2nd gear is smooth. I thought it might be
due to the lift but a friend thinks it might be a gear ratio issue or
transmission problem. The clutch is solid so if anyone knows what
might be causing this please drop me an e-mail, ASAP as I am
purchasing at the end of the week, I hope.

Thanks JCO