I would not put the old plugs back in. If anything re-gap the new plugs to 35-38. Make sure the coil packs are fully seated on the spark plug. If they are not they can still fire the plug so the car will run but not efficiently. I would start here and then go from there.
FYI I run a gap of...
5.4 4v
2.3 TVS 140ci with 4 lobe rotor pack
10% or 15% overdrive pulley depending on day
1 7/8 long tubes open header
Mono blade TB
Custom cams
Factory CJ crank rods and pistons
Liberty modified 6 speed
1 piece Driveshaft
9in rear 4.10 gear with a lot of strange engineering parts
Weighs 3270...
I sent him a 20x9 rim and told him to make them 20x11.25 so not sure exactly as it has been awhile but think it’s measure from outside to outside. Since they are widened going inward the offset is different but I don’t know what it is off the top of my head. No spacers of any kind are used.
Eric Vaughn widened them. He used a new barrel on the back side and then they were welded together by computer. He only uses a single weld, Weld Craft uses two welds by cutting the rim in half and adding a filler piece. They retain the stock Dura Bright coating on the face and he clear coated...
Running widened Alcoa rims, they are now 11.25 in the rear with a 305 Super Sport tire. Didn’t remove anything not even the rear shock dust cover. BUT the reared must be center with a adjustable panhard bar. Car is lowered with the Ford GT500KR springs