1999 civic manual d16y8 vtec no power

I have a 1999 Civic I recently bought I know very little
about Honda civics this is my first one. It has a d16y8 and
a manual trans the care starts fine idles good and even
revs prety good in neutral but when I putt it in gear and
start going it barely wants to pull itself or even brake
4,000 rpm I can’t even put it all the way into 5th because
it will stop pulling all together. The intake is off of a 97 it
does not have any of the coolant hook ups and I can only
plug one sinser on the intak in and I do not have the o2
plugged In I also have a pretty good exhaust leek do to a
missing donut gasket. ? Do u thank it is just due to the
sinsers not being plugged in and do y’all thank I could fix
my problem by getting an actual 99-00 intake and owing
able to pluc my sinsers in and plugging the o2 in. Thank
y’all for all the help