One last note on Fuel pressure.

You said you have checked it and it was Ok.. around 50, I think you said.

Well, a proper FP test involves 3 specs.
The first is with the REG vac hose ON, the next is w/vac OFF , and the 3rd is after 30 min for pressure retention test.
The first 2 are the important ones and have to be spec b/c if they are not , then the FP can be too high due to Reg control...if this is the case , you can have rich adaptation b/c the fuel duration is calculated by fuel rail pressure being spec.
So, those first two specs have to be checked @ idle and compared tp spec chart [ meaning, you are not just looking for FP, but rather , you ar looking for FP WITHIN spec, specially with Regulator vac hose ON] . FP with vac hose OFF is always higher than with vac hose on...and is too high for normal operation.

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A Dalton