My 90 5 speed , is in super shape , now at times the car as Im driving normal will put out a jolt and the tach drops , seems as if I lost all power , but then then it all comes back in a split second . What is this, any ideas . Thanks for any input . My guess is the crank shaft sensor . What a job that will be . Has a new cam sensor . changed the DIS with another DIS from my other SC , same thing . No change . DW