I live in Australia. I own a 2000 Ford Laser Hatchback which i bought in 2012 for $4000. I have been driving it for 2 years now, I got in a crash in early 2012 but it has been serviced. But i noticed more recently my car seems to be breaking down slowly or something. For example when i break it tends to make a crunchy sound… It's not smooth and easy. For about a year now I have noticed my car will suddenly slow down while I'm going 100 on the freeway but this generally seems to happen when it's cold weather or hasn't been warmed up properly but it's terrifying cos it'll suddenly go into this mode where it goes slower and slower even if I'm pressing down on the accelerator as much as possible, to the point cars are piled behind me and i have to pull into emergency lane. But sometimes the sudden slowness will only happen for 1 minute and it will jolt and speed back up to my original speed (90/100). This happens when I'm driving into a 60 zone as well, it will suddenly go really slow down to 40 and people will over-take me and i can't control it until it decides to go back to normal.
Why do you think this is happening? Is my car just breaking down or do i need to clean the fuel? What do you think needs fixing? I do plan to sell it sometime, what do you think is an appropriate amount to sell it for?