420A Random Misfire on all 4 cylinders

[estuardowrld]

Welp. This is my final hail Mary since i got the car it’s been having misfiring issues every-time i take the car on the freeway. I’ve changed every part i can think of.
Cam sensor
Crank sensor
Fuel filter
Spark plugs gapped at .50
Wires x2
Ignition coil x2
98 Auto ecu
Egr delete

Only thing i haven’t touched is fuel pump and injectors. Everytime i go on the free way in 4th or 5th gear the check engine light flashes and the dreaded codes come out. I don’t know if it’s a possibility but the old owner had wired in the ecu. Please help

 

[estuardowrld]

So i have the haynes manual and i started reading it and it has a page where if the engine is misfiring through driving speed range it has a checklist. Ige done everything but the fuel injectors and the vacuum leaks.

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[LA_gst]

I had random misfire as well on my 98 gst spyder and it was injector 1..make sure u replace with OEM .. I found a used one n worked fine for me

 

[estuardowrld]

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everyone i haven’t updated the post because i got covid again. Anyways i took my injectors to be rebuilt and i bought complete new IAC and i swapped the crank shaft sensor again. But now my car does this like cut that sounds like it’s gonna die then the rpm’s climb back up.

 

[LA_gst]

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everyone i haven’t updated the post because i got covid again. Anyways i took my injectors to be rebuilt and i bought complete new IAC and i swapped the crank shaft sensor again. But now my car does this like cut that sounds like it’s gonna die then the rpm’s climb back up.

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[estuardowrld]

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[estuardowrld]

also when i accelerate the car the rpm’s go down to 800 which is what my car usually idles at and it jumps up to 2000

 

[estuardowrld]

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[estuardowrld]

Example of the RPMS claiming back up