Chosen Solution
I changed the plugs and wires , oil and fuel filter on my 98 gmc sierra z71 k1500 with a 5.7 I had a wire on each side crossed over somehow and drove it before seeing the problem the second time looking . Now it burns about double the fuel and runs like it’s dieing on takeoff with a load on it , not to bad without a load , but it’s backfiring and spits a d sputters on takeoff and with or without a load tries to and does at times shut off when taking off at a light . Pulling up codes low air input at MAF and cam shaft position sensor, I’ve changed the MAF but no change .
reckon you may have fried or gas fouled the spark plugs at those two cylinders you had crossed? if so, those cylinders still may not be firing, meaning your power is down by 25%, and might also be dumping raw fuel into catalytic converter, impeding exhaust, etc., at the same time. replace those 2 plugs first, i would guess.
