'91 Pioneer 2wd Long Bed Renovation

[Randy90MJ]

1991 Jeep Commanche Pioneer - 4.0L Rennix - 2wd - Long Bed - Automatic

 

Alrighty Folks, 

--I have been so lucky to acquire this Jeep from a very good friend of mine right before they passed away.  He and I had a few plans for the Truck.  But him being the Jeep finatic of us both leaves me in a pickle for what parts to buy, what parts to upgrade, where to buy said parts from etc.

--The Engine deifinately needs a makeover.  A little over 200k on the clock.  First time i crank it when its cold, it will fire up, sometimes a small skip, but not common.  After running for 60 seconds or so the engine will start surging.   If i unhook the IAC it will stop surging but won't run right.  If i leave it alone and try to keep it running with the accelerator itll run about 5 mins and shut off.  Not completely sure...

--------I know there was a fire under the hood a few years back that burnt up the Air Intake Piping to the Throttle Body.  This is one of the Engines that has a flange fit over a rubber foot extended from the Air Intake Hose.  Nothing else looks like it got crispy but hard to say.  

--My questions being:

1. WHAT replacement parts should i buy for this and WHERE should i buy them from?

2. WHAT Test would you recommend I do to narrow down the problems?

3. I also have another 4.0 High Output that need rebuilding. WOULD it be better to rebuild it and put it in or keep the Rennix?

[89 MJ]

Looks like a good starting point. 
 

I would recommend you go through all of Cruiser’s tips first. In the grand scheme of things, the HO engine really isn’t any better than the Renix. The cylinder head is better depending on the year, but that’s it.