i am just looking for a little help with my brothers car , its a 1987 toyota celica st and its a 5 speed. now i know that this is for hondas and acuras but bear with me its not my car and this is sort of a generic question.

the problem is upon acceleration the car jerks back and forth op to about 40 miles an hour. if you hold the clutch in just the right spot the car doesnt jerk, but that isnt too healthy to ride the clutch all the time. can anyone help?