So to start I’ve done hours and hours of searching on all the forums and no one really seems to have a resolve for this issue.
also I have replaced the following things.
in tank fuel filter
spark plugs
timing belt done at 100k
cleaned maf and throttle body.

car is a 2004 factory 5 speed with 176k on the clock, runs like a dream only modifications to the motor are a Srt intake from previous owner.
so when accelerating through the rpms the car will get to 4000 and it’s just bogs down hard, I have to shift up to get power back. This only happens when I’m not at full throttle, even at full throttle the car sputters between 4000,4300 and then seems to pick back up.
I’m at a loss of what to do.
I see a lot of people replacing the VVTI gear for oil leak issues but not for this problem.
Any input would be welcome.

 

It might be the vvti solenoid (known as the OCV (oil control valve) on these cars. There is also a cleanable screen underneath it you might inspect. If you have a scanner that shows live data, look for a good smooth throttle and APP sweep. A worn, or dead spot, or brake in the potentiometer of either of these sensors would cause an issue. No codes ever come up?

 

May be a bad TPS sensor. I assume this just started happening with no other changes recently.

 

Ok I will grab a scanner and get some data to see how the car performs and check that valve and see how clean it is. I really just want to get the car running like factory. I’ll update you guys what I find. Thanks for the input!

 

I'd put the stock intake in and see how the car runs (or even another aftermarket like AEM, K&N). The SRT has an ecu box that intercepts the maf signal - if that box has an issue it won't matter what parts you throw at the car.

 

Alright so been troubleshooting pass couple weeks I removed the srt intake and disconnected the tune box to try that route with stock intake and saw no change in the cars behavior.
i just replaced the vvti solenoid with a brand new one from Lexus and, car still has the same issue. I really don’t know what else could cause this, Boggs hard half throttle when vvti comes in and full throttle it hesitates around the same rpm range.

 

TPS or APP sensor.

 

I have this same problem right now after a full timing belt, vvti gear seal rebuild, vvti filter, seals, and throttle body cleaning.
The idle at warm is 1,200-1,500 rpm. Brake booster also intermittently loses vacuum at low speeds.
Car bogs up until 4k rpm.
I ran Techstream to monitor the system and getting timing advance of 17 degrees during idle.
I've checked all the vacuum lines and tightened everything.
Car has a P1349 for vvti system too.

I'm not sure where to start with the problems which happened after doing the maintenance.

 

You didn't happen to break a tooth on that tiny bronze retainer gear plate thing when replacing the main crank seal? That's usually what does it, I would double check that.

 

I had this EXACT SAME issue/problem with my 02 5sp IS300 and couldn't figure out anything after a year or so! Cleaned everything, swapped plugs, battery, etc etc etc. ******Decided to change the MAF sensor and BOOM! PROBLEM SOLVED!!! I had dismissed that from being the problem since it wasn't broken and never threw a CEL like a broken or "bad MAF sensor normally does, but it worked. 100% changed the car bad to where it used to be. I had the SRT intake, Dezod Green headers and exhaust. Hope this helps!

V.

 

I’ll defiantly consider this did you go with any particular brand of maf sensor?? I was looking and the denso one is $129.

 

Beyond excited right now replaced the maf sensor and all is well I’m surprised at how much better the car runs now it feels so good to be able to rev the car out!!!! I love the sound when vvti really comes in. Thanks to everyone who offered suggestions