if im driving and my speed ometer at times goes to zero then seconds later goes back to the correct speed... what does that necessarily means... is it a major thing to worry bout ...

Nah, it's minor. You might want to pay attention to what RPM's match common speed limits in your area.

No it doesnt mess up my driving... won't notice it til u see it doing so.. what about when putting it into gear and it jerks... is it a tranny mount or motor mount that is needed...

idle speed too high maybe ,should be 700 rpm,bang on dash bad connection at cluster,

Depends on if your car has an electric speedometer or mechanical. If electric could be bad sensor or loose wire in system, a dealer should be able to determine if thats it. Could be loose connection in dash but if that more things would probably stop working because most components in dash cluster use the same connection. If mechanical have driven gear checked. To determine if electrical back up car if speedometer registers it's electrical if not it's mechanical. I don't know when they changed from electrical to mechanical. Engine RPM has nothing to do with it. Outside possibility it could be ignition switch. Hope this helps.

"what about when putting it into gear and it jerks... is it a tranny mount or motor mount that is needed..." -- probably both ..it is a twenty one year old vehicle.

Just experienced similar episode. Was driving and speedometer dropped to 0 out of nowhere. Really weird