Can't seem to find the problem..

I have a 1997 Grand Cherokee 4 liter inline 6 cylinder Select-Trac that is having an issue. About 3 to 4 months previous to this problem she would stall and die and not start at all for a long while. Replaced the crankshaft position sensor and the issue stopped and did an oil filter and change a week or so later. A couple of weeks after that is when this started happening: Besides running rough and a lack of pick up an go that used to be there, after traveling about 15 miles she stutters and stalls. Pull over put it in park and turn ignition off. Turn ignition on and she'll usually start and run but may or may not die again soon after. We have done several things to try and resolve this and/or just needed to be done while we were there: New timing chain and gears, new distributor cap, rotor and plugs. Replaced downflow O2 sensor and ignition coil, power steering hose replaced because of a leak, replaced PCV valves on the head and put a new head gasket on. Replaced throttle position sensor and camshaft positioning sensor, new front sway bar links, front and rear shocks, rear brake pads and rotors and emergency brake pads. Fuel pressure at fuel rail test point sits at 49 psi. She passed emissions with flying colors within the last 72 hours. Mileage is 283,274.

 

Check the thermostat and waterpump. Also check the engine ground. Any bare or frayed wires?

 

Maybe the crankshaft position sensor is failing again? Parts these day are not what they once were I would try and get an oem sensor. Fuel filter? I don’t remember the years but the fuel filter had the regular built into them in the grand cherokees

 

Codes?

 

I would start with the easy stuff first. Is it an electric fail or a fuel fail? If electric, I would check the ground and negative terminal on the starter as @258 Rocket suggested. If it's fuel related I would check the fuel filter as @SmittyJeeper said, and make sure your fuel line didn't get re-routed too close to the exhaust along the way. My brother had a 74 Blazer that we fought with for months to figure out it was vapor locking after he put headers on it.