Yatagarage

So I have a 1991 NA and I recently did a swap with a 1999 NB engine and I have been having some idling issues. At random times it will go up to 2000 RPM and then sometime it will blow the 30A inj fuse and cut the engine. Not to sure what going on with the idling but I believe the wires for the injectors harness may have some sort of grounding issue maybe. Please let me know if I'm on the right track and some advise for idling problems like this would be nice.

Thanks!