2001 V70-T5. Performance-Reduced

[Y623RTP]

Hello All,

On Friday I was driving at about 60 MPH at steady throttle when the dreaded "Performance-Reduced" appeared and I became a slow moving hazard to others. I tried ignition off then a re-start but no-good. Had to pull the ECM fuse (6) in main fuse box. Then managed to get about another mile then it happened again, this time very close to home. No codes obviously for the first event, but there were for the second.
I read the fault-codes stored:- P-1618, P-0121, P-1603 & P-1608. Unfortunately no freeze data. I cleared these codes.
All was then OK until Tuesday evening. Then at about 40 MPH, accelerating, I again got "Performance-Reduced" which cleared after just an ignition off then a re-start. However, in the next 2 miles on the way home I got the same problem recur. I carried-on to home, parked and read the codes. This time very similar:- P-0121, P-1603 & P-1608... but this time with freeze data for the P-0121 code.

Freeze-Data
Closed-loop O2 for fuel-state 1, nothing for fuel-state 2
6.6 % engine load
Coolant-temp 79 C.
ST Fuel-trim B1 -3.91 %
LT Fuel-trim B1 0 %
Engine speed 2320 RPM
Road-speed 50 MPH

Is this throttle-pedal sender or throttle-body problem or something totally different ? What do the P-1603, P-1608 and P-1618 codes associate with ?

Any information greatfully received.

Ian.