Check engine light

[Seeker]

OK, 93 VR Calais on long trips with or without cruise control on, and usually on an uphill section the check engine light will come on. You can hear the engine change its tune but there is no loss of power or anything. I suspect that it could be leaning out, hence bringing on the check engine light. It makes no difference whether it is running on ULP or Premium ULP. Any ideas??

[Doctor Bob]

Without checking the DTC logged its pretty hard to tell
but the driving you describe maybe it yes
Rob