I just finished doing a head gasket and motor mounts on my 93 965 (original owner-176000 miles). The car ran perfectly for about an hour after completing the job, but during its first extended drive it went into 3 cylinder mode, stalled a number of times and finally had to be towed home. On board diagnostics have given me the 1-1-3 and 1-1-5 codes for both injector sets and I'm sure thats the problem as I've pretty well eiminated everything else(fuel pumps, relays ect.)All individual injectors check out fine and continuity between the injectors and the 53 connector plug check out with digital meter. After reading Tom Irwin's wiring harness info. I guess continuity check don't mean much. I'm willing to pull the intake manifold again to disect the wiring harness and look for problems, but I'd like to eliminate any possible components first. Other posts mentioned ground problems and I did change motor mounts. My 93 had no gound connectors on the drivers side motor mount. It has a ground strap from cam cover to firewall and two from battery to sub-frame and a lug on the engine block.I dont't think its a primary ground probem. The car would restart, run fine for about 2 minutes and then either go into 3 cylinder mode before stalling or just stall all together. Very frustrating. This motor has been flawless for 11 years and alot of miles. Looking for ideas.