went out to the 97 grand cherokee v6 4.0 2wd wont start mechanic thought it was the fuel pump replaced that along with crank shaft sensor still wont start replaced cpm works good but catalytic converter needed replace so that was also done.A month later it starts loosing power randomly at highway speeds and almost immediately regains power. had the alternator checked and they said a part inside it was going bad replaced the alternator. few days later still having this loss of power sometimes happening at stop lights and loosing all power but i turn the engine back on and it runs. Cleaned out throttle body replaced spark plugs still having issues. Take it to the dealership they say ignition coil, tps sensor , and crankshaft need to be replaced from the code reader they had when they took it out on the highway. I replaced all three still having issues. Drove it to work got there fine leave work it will crank but not turnover checked and there's no spark not sure what else to do any help appreciated