Probably a sensor failure.

HEGO/LAMBDA is a good bet to start with.

a lot of cars will run without the LAMBDA albeit not perfectly. A good test is to unplug the lambda and see if the car improves. A massively out lambda can cause massive overfuelling and usually the fuelling tables for non-closed loop will be more efficient than massive over fuelling.

could also be MAF/MAP depending on the car (not sure on scoobys) as most engines fueling is also based on the air getting into the cylinders.

could even be a coolant or air temp sensor as they too have an impact on fuelling.

Ideally get it on a diagnostics and see if it pops out a fault code. But you can check the lambda by unplugging it yourself.