Acceleration problem with 93 S13 (believed to be fuel)

[RPS13DRFTR]

whats up guys, yup, newbie here. Got question bout a problem with my acceleration. Pretty much been having this problem since I purchased the S13 but its getting more obvious now. Wondering if anybody else is having this problem or has had this problem. The first step I took towards troubleshooting this problem started with the fuel filter. replaced it and it seemed like it was running somewhat better. Then replaced the O2 sensor b/c had some slight hunting (plus figured it was time), well that cured the hunting and it starting running a little better. Then installed a Venom 400 and noticed a significant gain....so thought that the problem had been solved for the most part .....but I was wrong . After running it for about a week after the install of the 400 module, the problem started to come back again. So I thought that I had a really dirty fuel tank and the fuel filter needed changing again....well in the process of the change out looked at the filter that I had taken out and there really was no evidence of dirt in the fuel or any restriction in the filter. So that ruled that out.
Now to be specific....the symptoms are as follows; the more throttle you apply the more it wants to hesitate and studder, especially around 4 to 5,000 rpm. It just bogs down pretty bad at full throttle at those rpms while sitting still (not under load), but while under load and driving down the street it bogs under mid to heavy throttle only, it won't with light throttle however. And it seems like it tries to break free of the bog and accelerate but then goes back to bogging and slow acceleration. Some days it drives like a dream, but then right when I think that it has gone away it comes back.
I just purchased a set of fuel pressure test gauges and was planning on testing the fuel pressure regulator and fuel pump for efficiency, thinking that maybe one of these could be the problem. Or maybe it's the TPS? Or injectors? Not too sure ....
So if any of you guys know any solution to this problem and have anykind of good input, please fill me in. Oh by the way....I still have a Ka .
Thanks alot
If you would like to contact me...my contact is "[email protected]"

[nissanfanatic]

Try cleaning the MAFS with rubbing alchohol and Q-tip. Might be a fuel pump problem. I just installed a Walbro 255lph and my car runs like a dream now. Get some new plugs(NGK) and get rid of that Venom 400 POS. All it does is dump a lot of fuel in at part throttle giving you the sensation of full throttle at part throttle. Your car is not any faster after putting it on. It may have fouled out the plugs. 300zx fuel filter is good too.

[RPS13DRFTR]

Thanks for the advice man....Yeah I know that the Venom 400 just tricks the computer into thinking that it needs to give more fuel...just installed it for some kind of minor fuel upgrade, plus I just had it lying around the house collecting dust. Didn't plan on doing anything major to this engine since I will be dropping the SR in there anyways...just doing everything else in the meantime like the suspension and such.
Some of my first suspects of the acceleration problem were sensors just b/c of the way that it wants to jump in and out of bogging. Almost like the signal from either the TPS or the MAFS is fading in and out... so therefore the computer is getting mixed readings on like say how far the throttle is open or how much air velocity is coming through. That was my initial theory on the problem. About the TPS....was suspecting that maybe the fixture was loose and moving ....giving the comp. an inaccurate reading...but when I checked it by hand without moving anything it appeared to be fastened just fine. ....we'll see....I'll try cleaning the MAFS like you recommended and see where it takes me. Thanks alot and will let you know the outcome.

Oh yeah forgot to mention that I installed NGK Iridium IX's bout 1 yr. ago...I would think that they should still be good...
If anybody else has any good input then please reply.