So this has progressively gotten worse. Car hesitates under 4,000 rpm, from 4,000 rpm on it is fine. It started to miss at a idle and yesterday it wouldn't idle at all. So I removed the ocv and the filter and cleaned both car idles fine now but still has the hesitation below 4k even when in park or neutral. I replaced the air filter and swapped maf's still no difference. Any idea what could be causing this? How do I find a vacuum leak if it has one?

Thanks

 

Have you checked out the sensors on your throttle body? There is a helpful thread about the throttle body on here

 

update: I took the ocv and filter back out again and cleaned them with brake cleaner. I put them back started the car and seems to be revving like new. Car was cold obviously but the problem was warm or cold previously. Hopefully this does the trick. Should it matter if it is up to operating temperature or not?

 

Did you check the MAF sensor? my car was idling, and runing like crap in general with massive amounts of hesitation and poor gas milage. cleaned the MAF sensor, and the throttle response came back along with those issues dissapearing. What about last time you cleaned the throttle body? air filter? just a couple of smaller items to check and make sure it isnt causing the problem.

 

I replaced the air filter. How do I check the mass air? I have been getting codes for 02 sensors which could be the maf not sending enough fuel or too much. I sprayed some carb cleaner in the tb but I never took it off and physically cleaned it. Car has 208k on it

 

Only way to properly check for vacuum leak is with a smoke machine. (Puts 1-2 psi of smoke through your evap system and comes out where there's a leak) Garages will charge to do that though.

Have you had the car for a long time? When was the last time plugs & wires were done? Plugs are called for at 120,000...if they were done on time or early, it may be getting close to a replacement.

Generally if you have a MAF problem, it will trigger a MIL. Is the only MIL you've gotten for O2 sensors? To check a mass air flow manually, remove the part and look inside at the wires and see if there's alot of debris built up. If there is, try to clean it. If it's a circuit problem, cleaning it won't do anything....

Check plug condition, check MAF, re check for all current MIL codes...good luck!