Toyota Repair: car, toyota corolla, standard transmission

Question
my car is a 1992 toyota corolla and it is hesitating when i drive and go up hill after a couple of seconds then it goes into gear.
I just had a oil change  

Answer
Is it an automatic or standard transmission?
If it's automatic, check the fluid level first, if low add some fluid and check for a leak, if standard trans there may be a problem with the clutch, watch the tach, does the engine speed up but the car doesn't move? I need more information.