i have a 93z and when i put it in drive it tachs out around 4500-5200 at 50-60 mph.it wont shift and sounds like it is stuck in 2nd. it will eventually shift when i tach it out at 5700...could this be a VSS? clogged filter?

 

ok..UPDATE: car isnt stuck in 2nd..its stuck in D and wont go into OD..i changed Tranny Fluid and filter tonight but this didnt fix my problem..i also readjusted the TV cable..this wasnt the problem..so it is most likely narrowed to a Valve stickin in the valve body or the governer in the tranny..however something odd...when it wont shift, all i do is take the shifter and move to Neutral and back to OD and it will shift...someone PLZ help me.....