Limp mode?

It sounds like the car is in limp mode which will cause no power problem. We should start by running the codes to see what comes up here is a guide to help you.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

If no codes are present it sounds like the catalytic converter might be plugged here is a guide to test it.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

I would service the throttle bore as well it could be causing the car to go into limp mode.

https://www.2carpros.com/articles/throttle-actuator-service

Please run this test and get back to us.

Cheers

PROCEDURE FOR DIAGNOSTIC TROUBLE CODES P1126

1. Turn ignition switch ON and wait at least 2 seconds.
2. Select "DATA MONITOR" mode with scan tool.
3. Start engine and let it idle for 5 seconds.
4. If DTC is detected, go to "DIAGNOSTIC PROCEDURE ".

Specification data are reference values and are measured between each terminal and ground.

CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

DIAGNOSTIC PROCEDURE

1. CHECK THROTTLE CONTROL MOTOR RELAY POWER SUPPLY
CIRCUIT-I

1. Turn ignition switch OFF.
2. Check voltage between ECM terminal 104 and ground with tester.
Voltage: Battery voltage

OK: GO TO 5
NG: GO TO 2.

2. CHECK THROTTLE CONTROL MOTOR RELAY POWER SUPPLY
CIRCUIT-II

1. Disconnect ECM harness connector.
2. Disconnect IPDM E/R harness connector E121.
3. Check continuity between ECM terminal 104 and IPDM E/R terminal 47. Continuity should exist.
4. Also check harness for short to ground and short to power.
OK: GO TO 4.
NG: GO TO 3.

3. DETECT MALFUNCTIONING PART
Check the following.
L Harness connectors E19, F33
l Harness for open or short between ECM and IPDM E/R
: Repair open circuit or short to ground or short to power in harness or connectors if problem found.

4. CHECK FUSE
1. Disconnect 15A fuse.
2. Check 15A fuse for blown.
OK: GO TO 8.
NG: Replace 15A fuse.

5. CHECK THROTTLE CONTROL MOTOR RELAY INPUT SIGNAL CIRCUIT-I

1. Check voltage between ECM terminal 3 and ground under the following conditions with tester.

Ignition switch -
OFF = 0V
ON = Battery voltage (11 - 14V)

OK: GO TO 8.
NG: GO TO 6.

6. CHECK THROTTLE CONTROL MOTOR RELAY INPUT SIGNAL CIRCUIT-II
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Disconnect IPDM E/R harness connector E124.
4. Check continuity between ECM terminal 3 and IPDM E/R terminal 42. Continuity should exist.
5. Also check harness for short to ground and short to power.
OK: GO TO 8.
NG: GO TO 7.

7. DETECT MALFUNCTIONING PART
Check the following.
L Harness connectors E20, F32
l Harness for open or short between ECM and IPDM E/R
: Repair open circuit or short to ground or short to power in harness or
connectors.

8. CHECK INTERMITTENT INCIDENT
OK: Replace IPDM E/R.
NG: Repair or replace harness or connectors.

Are you still getting any codes?
Check for vacuum leaks.

You're welcome.

Happy New Year.

Have the computer scanned and record the exact code numbers being set.

You have issues in the "drive by wire" circuits and it's going to take so very in depth testing with equipment you likely don't have to get to the bottom of it. I woulds suggest finding a competent shop to do some diagnostics for you.

Apparently not the right one. This is not a job for your neighborhood Firestone or PepBoys. You need a shop that specializes is auto electric or the dealer. The dealer is always a last resort.
This is really something that a good driveability tech would have no problem with. They just have to go through the circuit systematically using a DVOM, high grade scan tool and lab scope. And they will find the problem

Hello,

Here is a guide that will help you fix limp mode

https://www.2carpros.com/articles/reduced-power-limp-mode

Please run down this guide and report back.