So Here's my little project. 1987 PF was completely immaculate, like it had never been driven, 700$ with a bad z24 motor. I found an '89 Hardbody 2wd at the local salvage yard, and made the swap. Now it runs perfectly at idle and through the rpms until about halfway (no tach so not sure of the number), but when revved up hesitates, and it's consistent. Cant go over 60 in 5th gear, and every gear has the same hesitation. My worst mistake in the engine swap was not labeling the vacuum lines, and I wonder if my problem is there. I followed a couple of amazing threads on here, (thank you fastboatman!) but none were exactly the same as mine. Here are a few pictures so maybe someone can see where I went wrong, or if there is anything you see that could be causing it.

Thank you!

P.S. The valve in the second and last picture doesn't appear to be supposed to be connected to the vacuum lines on the front of the air cleaner like I have them, but if it is not connected to vacuum, the car idles horribly. Disconnecting it does not change the main issue.

I don't know much about the Medusa of vacuum lines in there, but have you changed the fuel filter? Restricted fuel filters often can cause inability to reach higher RPMs.

You can download the 1989 Hardbody/Pathfinder factory service manual here: http://www.nicoclub.com/FSM/hardbody/d21_truck_1989.pdf

Welcome to NICO!

I did try that first thing since the rig was sitting for about 6months before I bought it. I borrowed both the Haynes and chilton books from the wrecking yard but they don't actually show much for the vacuum layout on the air leaner and that valve in front of it.

Thank you!

From what I can tell the vac. lines look correct,if you are still having an issue look at the coil wires. If the exhaust side is switched with the intake side this will cause a skip/cutting out starting at around 2500 rpm. Don't ask how I know this......smh

jdan, thank you!

That hadn't occurred to me. I'm not gonna lie, I was excited to try it when I got up this morning. Unfortunately, it made no difference at all. In fact, swapping the coils didn't change anything about how it ran at all, which seems somewhat odd to me. I've been staying away from the ignition side of the equation because there is no hesitation at all in the engine if you can reach those rpm's while not under power (like downshifting on a hill) but the second you touch the gas it won't go at all.

Also, I've been thinking about this to see if anyone knows, is there a way to eliminate most/ all of the emission related components? I live in Northern Montana, and there is no such thing as emissions testing here.