Yes, many things. First do you have any trouble codes? Loss of power at any speed almost always pertains to air (vacuum) either leaking or blocked. That's an inexpensive place to start. Test all intake vacuum including egr and pcv with a inexpensive vacuum gauge.
Other possible things to look at is dirty fuel injectors or a small stone in the fuel line between the filter and the injector but these possibilities are more labor intensive and not as common.
are you hearing and strange hissing sounds ? check breather pipes all round look for any damaged pipes. some times squeezing them, also check the breather for the auto box.. on auto box clean all the road muck off and then go for a drive and then check it, look all round. do these checks. if nothing is damaged or leaking then you need to check the sensor. it could be clocked up and might just need cleaning. switch is located next to the oil filter. original colour is yellow if replaced it will be black color.
It sounds like you may have a bad head gasket or even cracked , When the car get warm it opens up and if your rad fluid is going it your cylinders and causing the car to misfire and smoke . The easiest way to tell the health of your motor is to do a compression test and look at the oil and rad fluid .
If you changed fuses maybe it's just come back on , if the alarm isn't sounding I doubt that's it , red flashing led's on the dashboard usually are an indicator that there is an alarm but not necessarily mean that it's been triggered
The simpplest way without any equipment and it's a fast test. Have a feiend with you,wire from the distributor cap, hold it about 1/4 of an inch from a clean, non painted metal object and have your friend crank the engine. If it's good, you will see a spark jump from the wire to the metal object.Note:keep your other hand off the car, it can zap you if it's good and the wire insulation is not thst good. This is a fast test, but it really doesnt mean that there arent other components which keep the coil from fireing.. Good luck.