Been running good up until yesterday. Now on start up rpms go to 2200 then about 20 seconds go to 1500 then 30 seconds settle at 1200. They go no lower than 1200 in park and then drop to 1000 in drive. Way too high.

Now I am getting codes 442, 456 and the dreaded 420 cat code.

Evidently I have developed a vacuum leak, BUT WHERE? Are there any special areas that are more prone to them than others? Mechanic told me to get a can of carb cleaner and start spraying the hoses and I will find it/them.

I understand the dealership does the smoke tests but for the money and time in the shop they want to do that surely I can locate something. Can anyone lead me in a starting direction? 2003 quad cab with 4.7

PS: Oh yeah, just for the waste of time I put a new TPS in with no change and unplugged the IAC and that made no change.

 

Just start tracing your vacuum lines.

 

Finally found my air leak that was really affecting the idle. Breather tube that connects to back side of intake down low, cant even see it. Its a hard plastic line I believe from the pcv valve but has a rubber 90 that connects to the intake, the rubber had a big split. Im trying to find this 90 but orilleys dont even show this on the back of the intake. Im attaching a pic of some intake pic i found on youtube. This was really making my truck idle high, upwards of 2200 on start up then never below 1200 in drive.

 

I have an 2003 dodge ram thunder road laramie. My brake light is staying on while the truck is switch on or while crank up. Third brake light works fine and no brake light come on inside the cluster. Have already switch out the brake light switch and bought two tail light circuit board panel. Buy all three from the dealership. I'm still having problem with the brake light staying. If anybody had this problem and know how to fix. Please let me know

 

I replaced both on my neon & 5.7 with a longer piece of straight hose they sold at autozone I had them match as my plastic piece had cracked, that leak took me weeks to find with 2 of use blowing cigar smoke an holding flashlights in the dark lmao.

as for the brake light switch did you replace it as well? Ive never had one do that other then just needing adjustment slightly

 

Mine also developed a high idle, sometimes. Lol stalls out after highway speeds but will restart. Im going to replace my iac and see