Brokenlexus95

So I'm trying to find where I can buy an alternator fuse for my 98 es300.I've searched on eBay and many other online stores but have not come across any place that sells those fuses.Please help!!

Car runs and drives but doesn't go past 3rd.Can't I find a computer for about $100 online and put it in myself? How about unconnecting the EFI fuse for 5 minutes? Can that solve it?

Battery in my 98 es300 died so I tried jump starting and accidently put negative onto positive.Replaced battery with new one,but having problems with most of my electricals.Lights work but other than that everything is dead.My cluster won't turn on,blinkers don't work,radio,ac,windows,locks,seats don't move,basically everything will not work.Also when I try to move car out of gear it will not budge.Car does not go past 3rd gear.Please help? Car was perfectly normal the day before.