ok figured out my last problem need help again

i have a 1986 nissan 200 sx and the car is just putt puttin along its like bucking when i first start it in the mornin then i go to school and about 30 minutes after its ok but it stalls sometimes and every time in the morning throughout the day it just bucks goes up to 2 rpm's and bounces down and up liek crazy plz help me if ya know what it might be my friend says it might be the tps plz let me know