Urs4 idling rough and not boosting normally

[Palakasana]

So, I have a 93 urs4 and I've been having a problem with it for a while now.

Its running/idling rough, just like running on 4 cylinders, but still running rich. Its running on all 5 cylinders though
And the boost problem is that the s4 doesn't boost over 1.5 bar looking from its own "computer"

The s4 is "basically" stock, only physical change is a fsi conversion, but it has ran fine with/without the fsi conversion. And it has a chip, I don't have knowledge of what chip it is, but it has ran fine with that also.

The car doesn't give any fault codes, apart from a 65535 from the ecu, meaning "total ecu failure", but that can be from the chips checksums?

So, what i have tested so far:
- Maf has been tested with some bentley guide, and pulling the connector of doesn't help (from reading forums, many say if its a boost leak, unplugging the maf helps)
- injectors/fuel supply
- Boost leaks hoses etc., except the intercooler
- Plugs/coils
- ECU wiring/insides, nothing seems to be wrong
- N75 tested

All new ideas welcome, i can test some components again if that helps, but I don't know what to look for anymore.

[Tractor Dave]

Do a boost leak test from where the maf connects ( smoke machine works very well) up to 10 psi. Have you replaced the valve on the pcv circuit? Have you done a fuel volume test?

[Palakasana]

I will do a boost leak test this week, my friend has a ”leak tester” set, but i have tested the fuel pressure and the volume, both are within specs. For the pcv, i havent yet changed the pcv valve

[Tractor Dave]

Audi still sell the pcv valve. Best get one from them. Aftermarket quality is dubious.

[Crasher]

Febi valves are good.

[tekstil]

Engine timing? O2 sensor and its circuit?

[Palakasana]

Engine timing ok, 02 sensor ok, tested and working. Circuit also working fine

[Palakasana]

Do a boost leak test from where the maf connects ( smoke machine works very well) up to 10 psi. Have you replaced the valve on the pcv circuit? Have you done a fuel volume test?

checked both the one under the IM and befind it, the one under was clogged (now open, cleaned it) and the one behind was broken, ordered a new one, will be arriving next week. I might in the meanwhile test for leaks.

but now it runs a bit better, still quite jerky, but the breather valve might solve that?