Jumpy Speedometer in Ford Focus

My daughter’s 2002 Ford Focus has developed a problem where the speedometer intermittently jumps all over the place - 0-90 and back, no matter what speed she is driving. The radio volume also intermittently jumps. Weather, speed, and cold start don’t seem to make a difference in these incidents which occur sporadically but make it difficult for her to drive, especially commuting to work in 35-mph zones.



These problems developed AFTER she reported a problem with her blower which now only works on HIGH speed. (But we replaced teh faulty relay so the blower works but she still has the problems with the speedo and radio).



She’s a starving student and I can’t help her out much either. Can anyone suggest what could be causing the speedometer and radio surges and can this be fixed at a reasonable cost? Thanks in advance for any suggestions!