oil pressure gauge fluctuating and power loss

Took the CS out for the first time in a month. Drove it about 8 miles on the freeway. Car behaved normally.
When I exited, the car seem to lose power, a lot. It barely moved under it's own power. Looked down at the gauges, I noticed the oil pressure needle was fluctuating widely at the right side of the gauge (at 140 lb/in2). Luckily there was a red traffic light. I turned the engine off and on while stopped. The needle settled at the 70 (mid-gauge) area but still fluctuates quite a bit.
The car had a bit more power but still pretty sluggish.
Took the car home on the side road. Part of the drive was a 3-4% grade and the car could not generate enough power to keep the speed at 50mph, slowing down to about 30mph after 1/2 a mile. Luckily, there was no traffic.
Searched this site and google but no solution - only suggestion was bad sender but that didn't mention loss of power. ( https://www.ferrarichat.com/forum/threads/360-oil-pressure-weirdness.569370/ )
Engine bay smell test normal. No burnt clutch or awful/unrecognizable smell. Just the usual smell.
(edited) 2004 CS. 30K miles.

Any idea?

Also, will call the mechanic and post an update once the problem is solved.

 

neither check engine or slow down light.

 

battery was full. was on tender the whole month

dont have scanner

will try that - probably next weekend if cannot get into mechanic sooner.

will read about limp mode (more than one post suggested it).

 

can't drain oil myself. No knowledge. No tools.
has appointment next week. will discuss with mechanic.

 

I have seen slow down message before so I know what that looks like.
none this time.
could be 2 separate issues but happened too closely. Still, could be a coincidence.

 

could be. will find out next week.

 

So finally had the answer from mechanic.

The gas pedal potentiometer went bad. Pushing on the gas pedal did not register and hence no power.
At the same time, the oil pressure gauge went bad, leading to fluctuating oil pressure readout.
Weird that both went bad at the same time.
Replaced both. Now car better.
Will pick up car later this week.

On an unrelated note, only drove the car twice in nearly 3 months (the second time was to the mechanic). I do miss driving it but not as much as expected. Was thinking about selling it as it is driven less and less. Not sure if there will be seller's regret.
Anyone in the same boat: driving the car infrequently, selling it, then regret selling it?