Engine help

[Jeepin35]

So I swapped a 98 XJ engine into my 89. Complete harness and computer. The lower end was junk in the donor so swapped head to my 89 block. Long story short.. engine will run but will die/stall. Fires right back up. Same thing. Can’t accelerate. Have replaced crank sensor, pickup sensor, injectors, fuel pump, throttle position sensor, MAF sensor, idle air sensor, new plugs, new o2 sensors but downstream is not in yet need to weld in bung. etc.. what I do notice is tach jumps around when it does start up? I’m about 95% sure timing is on. But going to double check tonight. Any help would be great or if anyone has experienced this before please message me thanks again 

[Pete M]

how long does it run before dying? 

 

are you absolutely, 100%, super-duper certain you got all of the factory XJ harness grounds re-grounded?

[Eagle]

To be clear: In addition to swapping in the 98 XJ engine, you also converted the electrics to the '98 engine harness and PCM?

[Jeepin35]

Runs for about 1min or so give or take. 

 

Yes complete swap dash harness and engine harness running the XJ tank and pump