RomRaider

Question: Would a custom tune likely help solve our issue?
Also, happy to pay someone to help us, if that makes more sense.

Notes below:
We bought this a year ago and the turbo was blown (had a blough? 3inch intake)..
It has a lot of aftermarket parts and custom cobb tune, I believe stage 2..

We just needed for a kids car, so I put a cheap turbo in it and worked ok for about a year.

Recently it had misfires and we replaced plugs, coils, injectors and maf and oxy sensors and cleaned throttle.

And it runs ok for a few minutes after clearing codes and then runs terrible and misfires all come back.

The replacement turbo has smaller intake, so a bit less air, and then the injectors are stock now.

Do we need a custom tune to solve, or is the problem perhaps with the engine? It has about 168K and we religiously change oil.

Thank you,
Alex