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Discussion Starter · #1 ·
1997 jeep grand cherokee with 4.0. This is my first time posting. First time owning a jeep running into some issue would like to see if I could get some help. Bought first day ran great, since than been having issue been having multiple cylinder misfires, super sluggish until about 4k, after that seems to have full power back. I've changed spark plugs, wires, rotor, cap, cps, cks, fuel pump, tips, may, checked all the computer connections, and all the connections I could think of. Starting to run out of patience and money and I've only driven it once. Can post videos if needed. Any insite would be greatly appreciated
 

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Procharged 2020 Jeep Grand Cherokee Trailhawk, 5.7 Hemi
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W E L C O M E ! ! !
... to the forum.

Check your timing chain. Sounds like you may have jumped a tooth or 2.

Relatively easy on the 4.0l, you are looking for excessive play in the chain, and/or that the timing marks on the camshaft & crankshaft gears line up, when cylinder 1 is at Top Dead Center (TDC).
 

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How many miles on it?
Did you scan the PCM for any CEL trouble codes?
How does it idle?
Whats a cks and tips?

One easy thing to check if its misfiring on multiple cylinders is the injector harness where it snakes over the engine to each injector and also where it sort of bends near the firewall. Check for broken, burnt or frayed wire insulation.
This was a problem on my old '94 4.0
If its misfiring on just one cylinder, could be an injector.

Some other things, bad ground, MAP sensor, TPS sensor, clogged CAT or muffler, vacuum leak, cam sensor and O2 sensors though that should show up as a CEL trouble code if you scanned the PCM for CEL codes.
 

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Discussion Starter · #6 ·
Sorry about taking so long to reply on here I am truck driver and away from home alot. But I changed out the timing chain and the gears. Runs better on idle still super sluggish. The milage is around 168k on the original post my phone auto corrected that was supposed to be throttle position sensor. The cks is the crankshaft position sensor. It hasn't been throwing any codes at me. I did notice that it started to run cruddy about the same time my over head console quit working don't know if that may have something to do with it or just being paranoid. As far as vacuum leaks nothing that I can tell of always used the method of spraying starting fluid around line to see if it changes the idle. I'll have to check the wiring harness in those areas next time I get home. Thank you guys for different directions to be looking at.
 
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