New guy, '91 KA woes (misfire on #2)

[Cuskiyo_S13]

Hey guys, new here and I am in need of some additional advice.

I have a all stock '91 240sx, and lately I have developed a misfire. It seems to only rear its ugly head after times of "harder driving" revving to maybe 5500, and is intermitent (I can go a week with no misfire). Here are things I have been through already:-checked all emissions control equipment.-swapped back to older set of plugs, and checked I was getting spark in #2. It is.-Cleaned the MAFS, improved performance, and intially led me to believe I had found the culprit but alas I had not.-checked all vaccum lines, everything is solid and intact.

It occurs after I have been driving a while as described above, makes performance sluggish overall, and is extremely noticeable below 2500 rpm.I have the intake manifold gasket, but before I tear it apart to replace that I want to hear some other opinions.

Thanks in advance!

[neverlift]

how are the plug wires? a very slight faulty connection can cause plenty of trouble... go ahead and replace the gasket it was only 10 dollars,yours may not need it but its always good to know you have good seals.

[chung300zx]

I had a misfire caused by a bad injector...hope that helps

[93HATCH240]

Did you end up changing the intake manifold gasket? If so how hard was it? Mine is leaking right under the fuel rail.

[jbrown]

I'm having the same problems and I cant figure it out... so any help would be awesome... ive replaced the plugs and wires, im going to do the cap and rotor once it comes in (had to order it)..

mine idles really rough when its cold, then it clears up... it seems to come back if the motors under a lot of load, but it's the worst after a cold start... the engine just struggles and you can hear the misfire.