First time caller long time listener. I'm having an issue that when I use heavy acceleration in my 2001 corolla LE Automatic the RPM and also acceleration seems to slow down then increase and repeat up the rev range. It feels as if there is a restriction somewhere kind of like a spot on the brake disk that is slowing acceleration down then releasing it every 1 second or so. Its not the brakes. I have replaced upstream o2 sensor and MAF with denso new parts. Coil packs are second hand but appear in very good condition from a newer series corolla. Fuel pump is a denso I got from a guy who said he never got to installing it on his car. Injectors are reconditioned Denso from a company that reconditions injectors. PCV Is around a year old and OEM. I've used a vacuum gauge and nothing indicates a vacuum leak. Perhaps it's my Catalytic Converter? I'm lost. Please help:) thanks so much
Sometimes the simplest things are the things that get overlooked. Check the belt AND the drive pulleys - if you have a bad bearing, a locked up condenser clutch, or a bad belt this can cause hesitation. To me your issue sounds almost certainly like electrical if it's not the drive belt including but not limited to spark plugs, bad battery connection, coilpack etc (although you would have a misfire code if a coil was bad). Rule out the serpentine system first though.
@inthedetails
Coincidentally I'm replacing the serpentine belt today:) thanks for taking the time to help! I'll let you know what I find.
@inthedetails
Replaced the serpentine belt and all the pullies span freely. The AC would spin longer than the others with the water pump being the slowest albeat still spins without any sticky sections. I think I may take a look at my battery cables as they are looking pretty dated
This is likely the electric issue.
Load test your battery and alternator.
@yaser
Well I went ahead and swapped just the battery terminals and the grapping releasing feeling on hard acceleration is much less now:):):). Its still there a little though and I think next I'll replace the complete cables themselves since the copper was a little black , more so on the negative cable. Generally now I dont have to press the accelerator near as much as I did before and I'm really enjoying my old car again:))
Glad to hear that.