looking for grounding issues

I have a 90 XJ 4.0, renix, it dies on me here and there, or just will not run some days, when trying to restart it turns over and will attempt to run, just a quick 1 or 2 cylinder fire, but once I let it sit for a while, it starts right up... So I'vr cleaned and reconnected all connectors under the hood, battery to block, block to firewall, and all sensor connections, so is there a large ground under the dash I need to find, or start looking elsewhere ??? Thank

Have you tested the CPS ? The CPS is the most common cause of stalling and no-starts.

TESTING PROCECURE for 1987 – 1990 4.0 L engines

Test # 1 - Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the CPS and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 – 275 Ohms. . If the CPS is out of that range by much, replace it.

Test # 2 - You'll need a helper for this one. Set the volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your helper cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. (That's between 1/2 and 1 volt AC.) If it's below .5vac, replace it.

Thanks, I haven't came across that test, besides folks saying just replace it

Also read the RenX files thread.

http://www.naxja.org/forum/showthread.php?t=905849&highlight=renx+files

While you're refreshing all the connections, which I believe is an excellent idea, pull the 4 relays on the passenger side inner fender and clean their terminals and spray contact cleaner into their receptacles. They can get corroded and one of those relays is your fuel pump relay. Given that you state it acts like it's trying to fire on a coupla cylinders, you're describing what happens when a fuel pump isn't pumping.