Lancer is Hard to Start Sometimes While Engine is Hot

[Robinsaneyo]

I have an '03 Lancer with 201,000 miles on it and the title explains the exact issue I'm having. It seems to be getting worse the warmer it is outside. It started out as the engine would sputter a bit on occasion when starting it hot or warm, now it's to the point to where I have to sort of nurse the car by pressing the gas pedal to get it to start when I have this problem.

I double-checked the air cleaner (which I replaced within 5,000 miles) and that's fine. I haven't dumped any "cleaner" into the gas tank as I'm a bit weary of those products. I've used Marvel Mystery Oil in the gas tank and the crankcase in the past, but I don't use it often at all.

The only two things I can think could be an issue are my leaking valve cover gasket and rear catalytic converter. The valve cover is leaking enough to fill the spark plug wells, but not enough to leak onto the ground. The front catalytic converter was replaced around 120,000 miles, but I've never replaced the rear one.

The last time I changed my plugs and wires (20,000-40,000 miles ago I think?), #1 and #3 spark plug wells had a bit of wet oil in them, but not inside the cylinder. When I checked this past Winter, #1 plug well was filled with oil, and all of the others had a bit of wet oil in them, but not filled. Once again, none of the plugs were fowled, and oil didn't seem to be leaking into the engine through them, not that I could tell anyway.

I plan on changing the valve cover gasket in a week or two, but I'd like to know if there's anything else I could look in to what could be causing the starting issue while I was replacing the gasket, or if anyone had any other ideas.

[jamesslcx]

Is the check engine light on? Could be a sensor problem. How does it run on the road? I run a fuel system cleaner through twice a year. Have you checked fuel pressure or replaced the fuel filter?

[Robinsaneyo]

The check engine light is on, it's for a small EVAP leak. It drives fine on the road. The only fuel filter this car has is a simple strainer in the gas tank, which I don't think is replaceable unless you also change the pump. I don't have a way of checking the pressure, but I guess the would be another thing look in to. Would I be having other issues if I had insufficient fuel pressure?

[jamesslcx]

Seems more likely it could be a sensor. Have you cleaned around the throttle plate lately? Low fuel pressure sometimes makes one hard to start but you would have some other symptoms like lack of power etc. Sure would be nice if there were some more codes set.

[Robinsaneyo]

I didn't think about checking the throttle plate, I'll check that sometime tomorrow.

Something which I didn't think of which might be an issue. I went away for 4 months, and the car sat that entire time. Long story short, I drove (well, limped) the car about 10 miles not realizing the complete lack of power was because a mouse had chewed through my air filter and made a nest. I imagine the engine sucked in a decent amount of crappy during those 10 miles. I didnt have a problem until about a year ago. Could something still be sort of lodged in the intake manifold?

[jamesslcx]

With vehicles and mice anything is possible. I would clean in and around the throttle plate and see if that helps. Use throttle body cleaner and let us know if it helps.

[Robinsaneyo]

Alrighty. I'll check out the throttle plate this weekend. I might take off the throttle body and clean that up a bit if I can. I'll let you guys know what I find. Thanks for the suggestions!