79 G25 350 engine
Ok this is what I need help with, this is not my van but my mom's. She says it runs good for about 15 mins, on highway and then hesitates, but when she lets off the gas for a while it is fine. Any one here now what could be causing this, she has replaced the spark plugs, carb was rebuilt, new fuel pump and filter, and new air filter. Is there something else she needs to do to make it stop running like crap. Please get back to me ASAP, and thank you for the help.