Ok, i took my car up to big bear which is at about elevation 8000 feet. On the way up, my car was running fine. In big bear, my car was running fine. On the way down from big bear, my car ran fine. Once I got to a lower elevation, my car seemed to struggle to hold a speed and accelerate. I thought that it might be the change in air pressure, but when it kept happening, I pulled off the highway. I thought it was the transmission, it felt like it was stuck in first gear and when i would accelerate, the RPMs would be really really high. My engine got hot, and my check engine light came on. I took it to the transmission shop, and they told me it was a fuel evap system problem. Took it to a regular shop, they replaced the part, and told me it was fixed. I drove it from victorville to fresno, and there is a stretch of hills and mountains that i had to traverse. My car struggled on the hills, and after the hills, it felt like it did before i got it "fixed". Does anyone have any ideas about what it could be, i am thinking it is possibly the exhaust, but i am not sure. I have a 2000 neon, auto tranny. Any suggestions would help, i need my car running right again. Thanks

 

well check all your fluids and maybe your spark plugs or spark plug wires

 

check your air filter, maybe

 

Yea, check the air filter.
That area is really dusty.

I remember driving the hills between Bakersfield and Las Vegas and the air filter was badly clogged.

If your from Fresno, you know how dusty it gets around there, especialy during the hot summer season when the farmers are doing burning and tilling.
The run between Hanford and Fresno sucked some times. The car would start out clean, and by the time I got to Fresno, I could write my name in the dirt on the windows.