As stated in topic, have a 1987 4runner with a 22re. I am changing the engine with a 1991 toy P/U. I see the long blocks are the same along with many other parts. But the wiring harness and ECM are different. Also there is a difference in the intake manifold, the 1991 22re has more room in the injector area and different throttle body's. But my first question,

The 1991 ECU has only 2 J connectors and the 4 runner has 3. I do not have a oem service manual. So my question is has anyone here done such a swap? ie all of the wiring harness or just a long block swap. I was hoping to change the motors complete with harness. As the older 1987 motors harness has been damaged quite a bit. Any advice or insight would be very helpful.

just swap your injectors and harness onto the 91, or install complete harness and ecu from 91 and compare dash side plug for changes

Most people doing that swap splice the newer connectors onto the old harness. If your harness is in bad shape that's a problem.
Maybe if you splice the new engine harness to the old ECM.
You'd need wiring diagrams for both, but u can find them online.

Are the dash side plugs pretty much the same?

i only have tore into the 1991 pickup so far.

So I have been doing a little research today. Seems this topic either is worded wrong on the internet or just not talked about much. I did find this though off offroadsolutions. (hope it is ok to put there name here)

"There are 3 primary parts of this OEM 22R-E fuel injection circuit. The first is the engine wiring harness. This is the harness that is primarily attached to the engine. This is sometimes called the injector harness. This harness connects the engine components such as the fuel injectors, ignition coils, etc. to the engine computer and the body harness.

The second part is the Engine Control Unit, or ECU. This is also called the Engine Control Module, or ECM. Sometimes it is just called the engine computer. This is the heart of the fuel injection system. This maze of solid state circuitry uses various input signals and outputs to control the engine.

The third part of the 22R-E electronic fuel injection circuit is the body harness. This is sometimes called the “dash” harness or the “main” harness. It stretches across the inside of the dashboard and sometimes into the engine bay. This harness is the largest harness in the vehicle and carries the majority of the vehicle’s circuits. About 45% of the 22R-E fuel injection’s wiring circuit is contained in this harness."

With all that being said, I had noticed the EFI circuits in the 1991 fuse box under the hood that the 1987 4 runner seemed to be missing. This was why I joined here and figured there had to be someone who had done such a rewire or adapted the ecu of the newer engine. I will add more as I find out things with pictures. I am sure more questions will arise. Thank so far for those that have answered

you will need to change a few pin locations, you will need both wire schems