My car keeps disengaging the gearbox as i am driving allong as if i have put the car into neutral and then after between 5 to 50 seconds it just slips back in and drives again this is very annoying as i loose all momentum and have to pull over regularly. Also takes a lot longer to change gear(5 seconds) than it used to so once again i loose momentum i know something has died in the gearbox but am unsure what i have a feeling it is the tourque converter but it may possibly be the spider gear just not sure please help as i need my car back on the road asap

Cars & Trucks - Mitsubishi - Sigma - 1990 Mitsubishi Sigma