Just within the last few days I did a tune up on the 300 (3.5L touring RWD). Replaced coils, spark plugs, air filter, cleaned the throttle body, and sea foamed the vacuum lines. Planning an oil change on it, but haven't done it yet. Did not replace the manifold gasket as it didn't seem like it needed it. All vacuum lines have been hooked back up, and all wires are plugged in.

Codes did not show up and didn't have any issues for a couple days after the tune up.

Getting codes for fuel system stuck in open loop on both banks and random cylinder misfire right at this second. Last night on lunch at work it kicked while in park and stalled out. Then when I was driving home and hit 70mph, it started doing that same hard kicking, would lose power, and then gain power again. Check engine light started flashing and traction control light came on. Pulled over and ran the codes, popped up the previous codes plus camshaft position sensor erratic signal and left front wheel speed sensor issue. Shut it off, cleared the codes, and seems to be driving fine again. Only problem is it randomly decides to flash the check engine light at me. It will do it most of the time at highway speeds, and sometimes when driving on backroads at any speed.

My question is: could it be due to an intake manifold leak? Do I have an issue with the computer? The fuel system codes, camshaft sensor, and wheel speed sensor codes don't make much sense to me. The cylinder misfire I figured may be due to messed up pre-gap on the plugs. Any input?

PS: it was raining last night and is this morning, I believe it is the first time since I've had it that I've driven it in the rain, but it was my parents' car before I purchased it from them and they never had these issues. Sat for a month or two between when they stopped driving it and when I started, but never had these issues before the tune up.

 

A few things:
1.year and miles on the car?
2. did you used the proscribed chemical & throttle body cleaning procedure? Failure to do so is a BAD thing.
3. reinstalling old vacuum lines with cracks is an easy thing to do.
4. were there issues before you started the tune up?

I can't see how the things you have done could cause a manifold leak. Do post the exact error codes so some of the more experienced dudes can weigh in.

 

I think it's important for you to find out which cylinder is misfiring and start doing some problem solving on that specific cylinder. I'm not sure about the 3.5l but the 3.6l it is recommended that you change the upper intake plenum gaskets whenever you do the plugs.