I have a 1998 3.8 V6 and I recently replaced the lower intake manifold gasket because it blew up and coolant was getting into the oil. Anyways, Fixed that, replaced plugs, Replaced injector o rings, changed the thermostat, flushed both system, Cleaned the MAF, the whole nine yards. Now, I've seemed to develop a strange misfire issue. Driving under light to medium load and keeping the engine between about 1500-2k rpms, the car becomes jerky and feels like its mis- firing. I've gotten no codes and the car runs fine above and below those rpms. Also idles fine. The Car currently sits at 130k miles and I just feel like im running out of ideas on what could be the cause of this. Any help would be appreciated, Thanks!