My '95 K1500 had developed a major exhaust leak at the manifold where it met the y pipe ( blew the connection apart ). Had to drive it like that for a while and it started to run funny. thought it was the exhaust doing it. So I opted for some headers and had a local shop I trust do the work. New shorty headers, new Y pipe, new O2 sensor and new plug wires. After that it ran better but still wasn't 'right' and was drinking gas.. Someone mentioned a ground, and I found the engine ground had been burned in half, so I got a new ground strap and ran it from the frame where the old was to the A/C bracket ( best I could do without getting too far under the hood ).. Evidently that is all it needed as it was fine since then and I was driving that truck until November.