need help with this

Ok im not an expert on cars but im learning in my civic this is the problem.
I was backing up and my buddy said he saw black smoke out of my tailpipe and when I set it in neutral and started tapping on the gas and I saw a puff of black smoke and my buddy realized that my car stalls when I hit the gas. When I hit the gas I got to wait a sec the car accelerate.

i put in a Short ram intake, headers (when I put this in low end power took a big dive.) so mechanic increased timing all the way and screwed something in the intake manifold (could that be problem?)

what engine swap should i get (93 civic DX)

if your looking for a cheap swap go zc or a6, other wise b16. black smoke means your running to rich, oh yeah drop your mechanic.

Have your mechanic (or preferably a new mechanic) set the timing back to stock. He probably adjusted the idle screw, so that may need to be re-adjusted after you change the timing. The reason you lost low end power was because of the mods you did. Short ram intakes are ment to make more high rpm power, and your header probably is too (since you said you lost a bunch). And by gaining that high end power, you probably traded it for a loss in the low end (basically you shifted your powerband). Modifications are a balancing act, especially for a daily driver/street car.