cold start problem
99 psd about a month ago the starter was going out, had it replaced and since then I am having a fit getting started in the mornings or late afternoons. Have checked fuses, had shop hook up computer to read codes and nothing came up. Gravity tested the batteries and showed a little weak, but full charged them and then load tested them with good results. Eversince the new starter, there has been a bzz sound when first turn the key, and the longer/louder the bzz the harder to start. I have tracked the bzz sound (sound like a relay shorting out to me) to a rectangular box under the dash in the center of the truck. I only have the owners manual, so no help there. Have had it into the dealer, but of course its warmed up then and won't replicate the problem. I have it scheduled to drop off for Wednesday morning so they can check it out. Once it has started and been warmed up, then usually no problems the rest of the day.
Also, once in a while it will act like it's got a miss in it, but that has only done it a few times and has never lasted more than 6 minutes. Really only noticeable while sitting at a light.
All help and info is appreciated.