[urq] suddenly lean

[spot.ontheroad]

I have a problem that has occurred suddenly. It's early days trying to identify the culprit but the symptoms are as follows:
If I accellerate hard in second, it pulls like a train and will continue to do so for as long as I hold the revs, the air fuel meter reads rich, showing the necessary enrichment is occuring. Then when I shift in to third the power goes, the engine stumbles and the air fuel meter shows suddenly lean.
The same happens when suddenly accellerating in third. It pulls well and is enriched, then when I shift to fourth the power goes, it doesn't want to rev and the mixture goes lean.
I have tonight had all the intake hoses off to look for splits that may open under boost. None found. The only thing I have done to it recently is change the oil and filters and put a new set of plug leads on it.
The motor is a WR with 7.20 CR, zener diode mod and a 1 bar WG spring. My boost gauge with tell-tale says it is hitting 1bar boost as expected.
Any suggestions gratefully received.
Many thanks

Keith

'87 WR

p.s. the 1988 TransAm footage was excellent.
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