My '05 Ram 1500 has 40K miles. It's in absolute mint condition. Recently (within past 6 past months) it would start perfectly every cold start (ie. very first start of the day). Wait about an hour or longer, it would sluggishly start. I poured over many threads to gain added insights. As such, I cleaned throttle body, replaced IAT (intake air temperature), crank sensor, cam sensor, cleaned all connectors to starter, replaced starter, replaced battery, checked alternator for charging (passed diagnostic test), fuel pressure is good. All parts used are mopar. I changed plugs about 10K miles ago along with PCV filter. Sometimes, I would have to depress pedal to start. Any suggestions?

P.S. One more thing...Never had any codes displayed.

 

Have you checked the injectors ? perhaps you have a weak one or just needs cleaned or new seal , check for any vacuum leaks along that line around intake area or anywhere
,,I found on mine by accident that exhaust was causing an issue ,,, mine was a little sluggish sometimes and I replaced the catalytic converters for different reason and broke them in properly and also complete new pipes an muffler and since that time it starts an runs better warm or cold but as I said I was having several issues

 

Is that a slow crank? Cranks normally, just takes longer to fire up? Doesn't run on all cylinders at warm start??

 

Yes. It does crank slowly and then fires up. While driving everything is normal. I thought about adding seafoam in vacuum line, but was not entirely confident this was wise to do.

 

I have not checked injectors. I need to determine how best to pull them and diagnose.

 

Looks to me you have already replaced everything that might be a contributor to the problem...... might consider installing another ground from the starter, to the frame.......

 

Is there a heat shield around the starter ? If its cranking slow like not cranking normal speed perhaps the starter is getting to much heat on it which Heat soak can usually be solved by installing a heat shield on the starter; this will reflect the heat away from starter , also clean all the grounds under the hood,,as it sounds like something limiting the the starter ,,like to much heat on starter or improper voltage or dirty grounds all can make a starter crank slow after its warmed up

 

There is no shield when I replaced it last year. Where can I purchase a heat shield for it? I will clean around grounding cables too. Like I said, the truck has been trouble free. Thanks for input.

 

It would not hurt. Thanks.

 

I see that there are two green designated bolts- starter body and solenoid. Perhaps attaching an external ground may help. Adding a heat shield could help; however, its never been a problem for 10 years!