S13 KA24DE Engine Stuttering/Lack of Power

Hey everyone!

So I've had my car for 2 years now and it has been great to me. Just a few months ago I drove somewhere for 30 minutes when it was really hot outside. When I was done and hopped in my car to leave, my engine turned over and the engine was running, but it seemed to be bogging out and stayed at very low rpm's (100-200). I stepped on the accelerator, but this did nothing, it kept sputtering like some old Harley for about 30 seconds, as if it were about to turn off. It kept on doing this as I tried to turn it back several times, so then I had it towed to a shop and they couldn't replicate the problem because once they got the car off of the flatbed, it started right up  It has been doing this sort of thing randomly once every couple of weeks. I start it up, it bogs/struggles at low rpm's, but the last few times if I apply the accelerator it will eventually come to a normal idle after struggling for 15-20 seconds.

And I also feel like there is a lack of power, as if it doesn't climb the rpm's evenly when I am flooring it past 4k rpm's or so. There is like a little pause/hesitation, and then the rpm's seem to continue normally. Could this potentially be a problem with my fuel system (my guess would be that the original fuel pump is starting to fail and is not sending enough pressure, or maybe a clogged sock filter). I've tried to look it up exactly, but how would I go about doing a fuel pressure test? Do I connect the pressure guage into the fuel line before the stock fuel pressure regulator?

The only mods my car has that I believe would affect the engine is a 3" exhaust that the previous owner had installed, and it still has the cat. converter. I have recently changed plugs and wires as regular maintenance (increase of 30HP instantly!  ) and have noticed no change with my issue.

I'm hoping to get this resolved soon so my car can be ready for the SlideSociety event on Sept. 28th!!  

Thanks in advance for the help and advice!

It sounds like a fuel issue or an air metering problem, which will effect fuel.

You are correct, fuel pressure is checked before the regulator on the rail.

Alright thanks. I will get one of those pressure testers from the auto parts store and try it out very soon.

And I have already taken my MAF sensor out and attempted to clean it, but maybe I didn't really do it well. If the pressure test doesn't give the news I'm expecting, do you think I should I buy a new MAF or see if I can borrow somebody's that I know works?

you can usually check the maf sensor by unplugging it with the car running, if there is no change then that would be your issue, if it runs worse then your maf is working properly.

I would lean on a fuel filter or a fuel pump, especially if both are still stock units from the early 90s

I'm pretty positive this isn't your issue
But it did happen in my old car. The car was so old and the cat converter was still on and it was so clogged up it would make the car hesitate and sometimes just bog out.
Now the reason I say it prob isn't your issue is bc you said it starts to drive normal after awhile

Just wanted to throw that out there.

But let me know how that fuel pump works if you use it.