The 22RE injection, especially the early issue, can't really handle much in the way of performance upgrades. Your regrind cam should be 220-240 degree grind with .420" lift. Keep your compression low, 9.5-9.7 to 1. I didn't like the early EFI, couldn't do much with it. If you can go carby it would be better, especially with a weber carb. You can look into a Cannon mani/38DFEV Weber combi and drop in a little bigger cam with a bump in compression for a kick in the pants improvement. For keeping the EFI I'd look into the late '89-'95 electronics.
If you don't have to worry about emissions look into dual carbs and a 20R head. Good power with an awesome sound.