Hey all. I just had an engine swap done a few months ago and have had issues with performance ever since.
I went from a 1994 EX Honda 1.6liter VTEC engine (about 109k miles approx.) to a J-SPEC imported 1.5liter VTEC engine (1996 or so) with about 40-50k miles on it. I'm hoping everything was swapped right. They put in a new water pump and timing belt in the process.
The problem is, most you already know this, when you drive your car all the time and for a number of years, you KNOW your car. And ever since i got my car back, it's just NOT the same. It drives very sluggest from the take off, almost like it's in 2nd gear instead of 1st, and here and there when i gas it, it almost stops like i switched the key off for a sec. or so, then on again.
So i thought maybe the original gas pump is just going out, but was told it either works,or doesn't work, not gradually goes, or sometimes goes, so i thought maybe it's something else in that case.
I also was told maybe they adjusted the timing belt wrong, as that could make a huge impact as well with overall performance.

I could really use some help here, as i am confused at what to do, or where to start checking with what the problem is. I have a friend that is usually pretty good with cars, and isn't sure what it could be from my explanation. But i would like to get it fixed, whatever it is. I only got an engine swap because it is low mileage and was told it's supposed to be slightly more horsepower then my factory engine, what i was told when ordering the engine (japan has slightly different specs on the engines, also since mine had 2ce the amount of mileage on it.)

If it helps, i still have the same transmission in it (auto), and i have a cold air intake, assuming the same fuel injectors, aftermarket exhaust manifold, highflow catalytic convertor, and aftermarket exhaust muffler, new fuel filter.

I do notice, sometimes when i'm moving, and gun it (around 5k rpms) i feel the slight power from the vtec kicking in, but then sometimes it's sluggest and don't feel much, like the difference of turning on your AC.) And again, when at a takeoff, it's most of the time sluggesh like the difference of a car (cold air intake on) in the winter, verses driving on a 98 degree hot day from a take off. And sometimes, it seems like it's stalling for a second or two like i switched the car key off, then on again.

Does anyone have any suggestions or idea's to try, or where to start with to fix this sounding problem? Thanx again ahead for any/all help. This is really irritating me. Wish i could figure this out. :-)