Escudo fuel use

The muffler indicator light showing indicates the catalytic convrter is bad.

For high fuel consumption, did you have a tune-up done yet?
Do you have performance related issues?

For the older models the catalytic converter is not linked to the ECM so it should not be the cause.

Spark plug leads would cause hesitation or misfiring but not pinging. If ignition timing is too advaned, pinging would occur. Is the ignition timing set correctly?

Was anything done prior to this occurring?

You mean the engine overheated after which the problems started?

Did you try retrieving for trouble codes?
Do you have the engine model?

When water gets to the ignitions system, hesitation would occur due to misfiring. Over time, oxidation occurs and continuity becomes bad.

Remove spark plug and ignition coil wire individually to check for bad contacts at either end. A good contact would look clean with no signs of oxidation.

Test the spark plug wires resistance. They should be 3 to 6.7 kilo ohms per feet.

Remove the distributor cap to check for presence of water.

The Catalytic Converter sensor does not control the computer.

You problem should be misfiring resulting in loss of power contributing to the higher fuel consumption resulting in the indicator light showing as the catalytic converter would be glowing red hot when excessive fuel gets to it.
.