1995 240sx .. tach and speedo dying? help??

[Carryl]

hey guys my car has 106k miles on it ... and i took it from ny to philli and back....on my way back home the car bogged at 70mph and 3000 or so rpm..for a quick second......and then it did it again a few mile down the road.... and i noticed... the tach and speedo guages drop as soon as it bogged.... like the tach started jumping and falling etc.. and the speedo just kept falling ...it did this 2 or 3 seconds... and then sorted out .....and then maybe another 50 miles went by .. and i noticed the tach was jumping and the car was stuttering again..and my dash lights were blinking on andd off.......im guessing.. its an electrical problem ? possibly a loose ground? or a corroded ground ?... help.......also.. i think its time to do n engine overhaul as i am thinking about turboing it ...what parts should i look to change?thanks Carryl Haynes1995 240sx s14