I have a 1992 f-150 4.9L with 270,000 miles. Its a 5 speed. For the most part it runs fine. I drive it every day for work. Lately my check engine light has been coming on and then goes off. It used to do it every once in a while, every couple weeks but now it comes on and off every day. It seems to come on randomly during the day and more so when it is idling. another thing I noticed is that my charging gauge sometimes starts jumping back and forth about 1/4" at idle and then will stop. don't know if they are related. The codes I am getting are 327 and 328. Both low voltage codes. The funny thing is that I just had it smogged last month with very good numbers and it passed. Any ideas?

 

Seems to be some EGR problems there.

 

your egr might have been sticking closed, i know mine was. some carb cleaner and time later, it worked! just an idea, pull the egr valve off and check it out