I recently removed the plug fitted to the thermostat on a F355 Challenge and fit a proper thermostat. Odd thing now though, although the car warms up thanks to the thermostat (whereas before it would run too cool under normal driving), now the car, after being driven for 10-20 minutes and at normal oil and water temps, throws slow down lights. The first time it was for 5-8 and if pushed one bank would momentarily cut out. Babied the car home. Checked everything (and did a synthetic oil and filter change for good measure) and all seemed fine. Took the car out again and it did it again. Drove a little farther and 1-4 and 5-8 lights came on as well as red slowdown light. But here's the odd thing. I looked for the dual ECUs for the cats and of course this is a 355CH so no cats. But there are no ECUs for the cats either. Car ran perfectly fine before installing the thermostat, albeit cool. Any thoughts on what might be causing this issue after I removed the plug and installed the thermostat?