hessitation or loss of power (searched)

[scs13]

i have a 1993 240sx with an s14 motor in it. i put the motor in about a month or so ago and it didnt do it or i didnt really recognize it doing it until a few weeks later or something. it hessitates sometimes and feels like it has no power usually in the low rpms, 2-3k or so but kinda feels like it has no power sometimes in the mid and high rpms. i put a new fuel filter, plugs, wires, o2 sensor, a different MAFS, tried to check all the vaccuum lines and emissions stuff. i searched and i cant figure out what it is. somebody please help me!

[scs13]

i promise i searched, trying to find a more clear answer pertaining to my specific problem. help me please?

[rogoman]

Several things to check:1 - Possible dirty air filter.2 - Distributor cap/rotor may need replacing.3 - Possible fuel pump problem. Use a temporary fuel pressure gauge to measure fuel pressure at various RPMs.4 - Possible vacuum leak. Use vacuum gauge to measure vacuum; should be around 20 InHg at idle. 5 - Fuel injectors may be dirty. Run some good injection cleaner, like Techron or Redline SL-1, through the system; Give the cleaner about a week or two to do it's job.

[scs13]

well i just cleaned that k&n filter before i put it on my car so its not that. put a new dist cap on it but couldnt figure out how to get the rotor off, so i guess i will try that. i ran some fuel system cleaner already but it didnt help any. and what vacuum lines should i check? how much is a vacuum gauge and a fuel pressure gauge?

any more suggestions if those dont work?

[rogoman]

A good place to connect the vacuum gauge to is the charcoal canister. There should be three hoses connecting the carbon canister. Two of the hoses go to a purge valve that's built into the canister. The second larger hose off the purge valve should be the line to get full vacuum.

Vacuum gauges and fuel pressure gauges can be purchased at many auto parts stores.

[scs13]

i found a hose that had a hole in it. dont know what exactly it was for, ran from the tb down to the bottom of the manifold. i replaced and thought it helped but it is doing it again really bad today.