Having mad issues

[s13inutah]

here's the deal I have a 93 240 with the ka24 and i'll be driving and suddenly the RPM's will drop to nothing and the car will kill. then it won't start for like 20 minutes to half an hour. i also found that after the last time it happened when i rev it past 4,000 RPM's the tach will freak out and go all over the place . any help you can give me will really be appreciated. i took it to a shop and it's been three days and they still havent even looked at it so i'm a little frustrated

[marshun]

whoa...my friends speedo does that. hehe