bad cables can lead to so many issues , i would go through all the ground cables and straps to make sure they are in good order and the connections are clean . It's never a bad idea to add some extra ground cables especially if your adding a lot of electrical draw to the system .
bought a 4 runner some years ago that was in really awsome shape but was always sluggish feeling once you got up in the rpm range , did all the normal things , t chain , tune up , cat , o2 sensors , coil but nothing changed the sluggishness. fast forward a couple weeks I was fiddling around with some other stuff and noticed one of the ground straps on the block was crummy looking so I went ahead and replaced all the ground straps and added a couple more down the frame to the body and bam !!! ran like a charm with way more power and I got another 3 mpg out of it . I think what lead to the ground strap failure is the kid I bought it from had a huge stereo system in it and with that constant overdrawing on the stock charging system it lead to the wires getting hot .
so long story short if your rig is used give them cables a look and it's cheap insurance to replace them .
