Pontiac Repair: whys my car suck?, 94 pontiac sunbird, pontiac sunbird


Question
I have a '94 Pontiac Sunbird LE with a 2.0, manual transmission.
My problem is that when I press the accelerator down too far, the engine sputters and the car starts to jerk.  It feels like it just completely loses what little power that it had to begin with.  
I blew a head gasket about a year ago, so I put in a new motor, the exact same style of motor.  Everything has been good until about a month and a half ago I had to have the catalytic convertor off and the guy at the garage just put a straight piece of pipe in where the convertor was(straight piped it).  It was good for the last month and a half.  But, lately if I press the gas down slowly, it will take off just fine.  If I slowly accelerate, it is okay, with just a little tiny sputter once in a great while.  But, when I try to get any passing power, or up-hill power, it just sounds like it is drowning, and the exhaust gets real loud and it sputters uncontrollably as it jerks like crazy.
What a pile.  I'm thinking possibly air filter, fuel filter, distibutor cap, or maybe just in need of a good tune-up.  Is there any way of knowing which one it is without fixing them all?  I'm a broke college kid who cannot afford to go through the process of elimination one piece at a time.
I would greatly appreciate any advice that anyone could give my sorry, ignorant a--.

Answer
Evan,
 Normally thats a sign of a plug wire or spark plug thats skewed. If money is a factor and when isn't it you could just go to a junk yard like pick apart and snag a wire long enough to reach all the plugs. Try it all around and see if it makes a difference or get new plugs and wires. I see this often and its the most likely cause.