Hello all, I am new to this forum and just recently I got this car from a friend who got it from an auction. Car starts and idles great But will not rev up and has no throttle response, A few times by holding the pedal to the floor with A/C off I can get it to SLOWLY accelerate in park, When I can get it past 4000 RPMs it has good throttle response until I let off the gas and then it turns back to the same thing. Got this as a project for me and my grandson to work on and it has really turned into a project, there are no check engine lights, There are not no fault code on my scanner with the exception of airbag, here is what we have done so far we have replaced the throttlebody, the mass flow sensor, the gas pedal and sensor and fuel pump and checked brake pedal switch, We also pulled the oxygen sensors from between the two catalytic converter’s And had exhaust coming out of those port holes, Also took tailpipe off of the second converters, We aren’t mechanics, he’s 13 and we’re learning together, next going to try to figure out how to do check fuel pressure and if anybody has any ideas please let me know and thank you so much.

The only way to check fuel pressure is with a sandwich adapter for the fuel damper, Z1 Motorsport sells one. However if it was a fuel pressure issue it would usually be WORSE at higher rpm.

Are you sure it's firing on all 6?

Is this a 5AT or 6MT engine?

Normally what I find with lack of power overall is something is pulling the cams and preventing cam advance, this makes the VQ INCREDIBLY sluggish if it can't leverage cam advance for higher rpm power.

How does it rev out in neutral or park? Still sluggish?

If you suspect a clogged catalytic converter you can just remove it, leave the downstream O2 sensors unplugged, then start the car and see if it revs freely. Again though a clogged cat is usually something that is less noticeable at low rpm but BAD at high rpm.

Do you have a way to watch realtime data? It would be good to know what your short term fuel trim is for both banks to see how much correction the ECM is making as well as how many degrees advanced the intake cams are at 2k, 4k, 6k rpm. Also you can check ignition timing with a timing light to see if it jumped a tooth on the timing chain which is very uncommon but should probably be checked, it should be 15 degrees BTDC at idle which is the MIDDLE mark, if you're reading the timing there's a mark farthest to the left which is zero, then two marks off to the right side which are 15 and 20 degrees.

What condition are the spark plugs, that will tell you a LOT about what's actually going on in each cylinder, if you aren't sure how to read them just take a picture of all 6 and post it here.

Have you checked for vacuum leaks? There are 3 PCV hoses, the PCV valve screws into the right side valve cover, make sure it rattles. If the intake plenum was removed make sure you didn't pinch the oil fill neck between the plenums.

Does it idle at 650rpm? Do the rpm's drop for a moment when you give it throttle at idle?

Have you performed the idle air recalibration since you removed the throttle body? Also the throttle closed position, APP released position, ECM reset (for fuel trim). I would do all 4 resets, they're in the FSM section EC - Engine Controls under "basic service procedures". It doesn't require any tools, just do the pedal dances method under "without Consult-II".