Beforehand, I recently replaced the camshaft plug and torque down everything as per http://www.lvracingscene.com/forum/s...al-replacement .
But now the car hesitates to accelerate whenever I push the throttle past 50% and it does not matter what gear I am in, as long as i push it past 50% the engine hesitates to accelerate and the exhaust makes the sound of an old classic car would make.
edit: I also notice that when the engine is hesitant, the check engine light would come on, but goes away when the I let off the gas.

 

when was the last time you did a tune up?

couldve damaged wires pulling them out.
could be not pushed on plugs all the way.

If it were me, Id do a full rotor,cap, wire and plug replacement

 

I replaced spark plug wires & plugs about 3-4 months ago. Today I ended up opening up the dizzy cap, to find out that the rotor was kind of loose. After tightening the bolt, I notice that the hesitation only happens when I am driving at ~2k-3k rpm, with no check engine light this time.
Thank you for responding
By the way, do you or someone know the exact torque specs for b16a2 cam cover? I know it says 16 ft-lbs for bolt #1-10, and 8 ft-lbs for bolt #11-14.
But when i compare the exhaust cam cover bolts (the cover that I took off) to intake cam cover (the cover that I never touched), the exhaust cam cover seems a lot easier to loosen the bolt, which lead to me believe that the torque must be higher than 16 ft-lbs.

 

I'm sure you figured this out but if not I would replace your cap and rotor. For the torque specs a bolt that has been at the torque longer is going to be seated better and harder to break at first then one that was just recently torqued into place.

 

Yes, I am in the process of replacing cap and rotor, but I was wondering if reinstalling cam shaft cover (wrong torque, etc) would cause sputtering in engine @ low rpm (2k - 3k rpm), or is it just coincidence that I was working on the car, and the dizzy cap and rotor fail.

 

It's just a coincidence especially consider you already opened the cap up and the rotor was loose,

 

Now I have pinpointed the exact problem, the spark plug in cylinder #4 (closest one to distributor) is half broken. Half of the plug is still stuck in the engine. New question, is it possible to take off the head without touching the valve spring etc (Just take off timing belt and certain bolts and remove the head?)