Recently bought a 91 Wrangler with 2.5 4cyl. It started randomly losing acceleration in 2nd gear as though it were out of fuel, I would pump the gas to no avail, then after 10-15 seconds it would act like nothing was wrong and run fine again. This problem has become increasingly more frequent and now it has trouble starting. Once it does start, it will sputter for 30 or so seconds and a popping noise can be heard in the air filter box, like I'm popping corn in it. Please help. The check engine light is not on so I'm guessing I'm not getting any error codes.