Speed sensor or fuel injector?

Ok for starters my car is a 1991 dodge shadow, 2.5 liter non-turbo, 183,000km. Ok heres my problem a few weeks ago I had replaced my timing belt, head gasket and intake/exhaust gasket. After that my car has been acting really funny, on acceleration in first gear I have to rev the engine up quite high or it will choke on me and a few seconds later it will grab and away I go. And in any other gear it does the same thing but not as bad. As well on a low rpm it likes to jerk almost like it needs more fuel. Now at first I thought that this would be a bad fuel injector as I don't believe that it has been changed but those cost $250, so I read in my haynes manual that a bad speed sensor can imitate the same symptoms as a bad injector. If anyone has any advice or has had the same problem please let me know