2004 Chey Optra lt engine light is on and there is loss of power ocassionally with some shaking of the car at speeds around 8o kms - took it to the dealership and the ignition wires & plugs were changed & the fuel injectors cleaned costing lot's of money mostly labour yet problem hasn't been resolved any ideas or suggestions

TOYOTA maker.
Toyota Land Cruiser Prado<<<<<this car?
Gen 3 Cruiser. with 4 petrol engines then.
no country told and is not USA car. we know that, but where? first sold
or VIN/
no engine told v6 size? 3.4 or 4.0L V6????????
wiki says the 3RZ-FE engine<<<< this?.for 2004
my guess ,is huge vacuum leaks.from lots of hoses even brake booster Vac leaks or hose never connected first.
IAC stuck open
TV stuck open on TB or gunked open
cutting out means stalling or just spark misfiring/?

getting too much fuel ,proved how? just RPM???????
the engine uses AIR, and this are he EFI adds fuel to mach air. mass.
that is how EFI works (be it mAF or MAP based)
online searching snows MAF sensor part of the TB.
some cars have idle only mAP sensor, but we have no books on this enigine.
let me explain MAF. mass air flow sensors
it measures ever microgram of air sucked in to the engine
the MAF tells the PCM this and PCM injects on mass air flow measured.
if you have any kind of vacuum leak the engine goes lean and slows DOWN LEAN BUT NOT IN COLD ENGINE STARTUP ENRICH MODE.

but not all engines witH MAF, SOME HAVE AND IDLE ONLY MAP SENSOR THAT IF VACUUM LEAKS HAPPEN THE ENGINE SCREAMS
KNOWING these to things, vacuum leaks
or in the MAF world UNMETerED air flow leaks.must be repaired.
all vacuum leaks are bad. besides, IAC allowed.

engine light comes on and you speed up dont do that can damage vehicle---have trouble code read most auto stores offer this service for free --a flashing means misfire or problem that needs immediate attention

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You may. Have a broken or disconnected wire

Is the Check Engine light on?

Trouble Code: P0846

A/T 2/4 Pressure Switch Circuit Malfunction
Possible Causes:


2/4 pressure is incorrect, or internal transmission faults exist 2/4 pressure switch circuit is open, shorted to ground or power 2/4 pressure switch is damaged or it has failed TCM relay power circuit to L/R switch is open (loss of B+) PCM/TCM has failed

Under the dash just left of the steering wheel.
Cavity Fuse Color Description F1 -- -- Spare F2 -- -- Spare F3 10 Amp Red Headlight high beam left F4 15 Amp Lt. Blue Flasher, hazard switch (see Junction Block diagram above for location of turn signal Flasher relay - Mopar p/n 4686094) (Repair tip: WJ flasher repair)
F5 25 Amp Natural Radio amplifier F6 15 Amp Lt. Blue Park lamps F7 10 Amp Red Interior lights F8 15 Amp Lt. Blue Overhead console, rear wiper, IP lights, rear flipper glass solenoid, power locks F9 20 Amp Yellow Power outlets F10 20 Amp Yellow Adjustable pedals (2002-2004 only) F11 10 Amp Red Rear window defrost indicator F12 10 Amp Red Auto shutdown relay / "Fuel" F13 -- -- Spare F14 10 Amp Red Headlight low, left F15 10 Amp Red Headlight low, right F16 10 Amp Red Headlight high, right F17 10 Amp Red Instrument cluster, diagnostic connector F18 30 Amp ? Trailer tow F19 10 Amp Red Anti-lock brakes F20 10 Amp Red Ignition Run / Heated seats / A/C Heater control / Flasher - Left and Right turn signal switch sense F21 10 Amp Red Ignition Run / Start - PDC (Power Distribution Center) F22 10 Amp Red Ignition Run / Start F23 15 Amp Lt. Blue Brake switch F24 15 Amp Lt. Blue Foglamps F25 20 Amp Yellow Accessory delay relay (sunroof) F26 15 Amp Lt. Blue Cigar F27 15 Amp Lt. Blue Rear fog (export) F28 10 Amp Red Body Control Module, Acc/Run F29 10 Amp Red Rear wiper switch. Washer motors F30 15 Amp Lt. Blue Radio F31 10 Amp Red Ignition Start F32 10 Amp Red Ignition Run / Start - Airbag F33 10 Amp Red Ignition Run / Only - Airbag C1 20 Amp Yellow Wiper (Circuit Breaker) C2 20 Amp Yellow Seats (Circuit Breaker) C3 -- -- Spare

I hope this helps :)

you need to read the code the engine light is on for

I do not know if you have the 3.4L or 3.8L Engine; however, I have included both below:

For the 3.8L V6:
Firing Order:
1-6-5-4-3-2
Cylinders:
(back of engine)
2------4------6
1------3------5
(front of engine)
Ignition Connections:
(back)
o <----6
o <----3
___
o <----2
o <----5
___
o <----4
o <----1
(front)

For the 3.4L:
Firing Order:
1-2-3-4-5-6
Cylinders:
(back of engine)
2-----------1
4-----------3
6-----------5
(front of engine)
Ignition Connections:
.........(back)
.|.5..2.|.|.3..6.|.|4..1.|
.........(front)

Let me know if this helped....