rough engine performance

[offthahizl]

I recently purchased a used 2000 4runner limited with 4w driveand about 193k miles on it. The check engine light comes on and goes off periodicaly. The code was P0305 (misfire cylinder 5). It idles rough and accelerates poorly. It shakes violently and a big power loss is noticable. I have replaced all spark plugs and wires. I also replaced the coil pack that is associated with cylinder 5. This had no effect. Today I cleaned the mass air flow sensor and the throttle body. When I started it, the check engine light was still on, it idled high but ran without vibration or poor acceleration for at least 30 miles. I thought the problem was fixed and decided to clear the code with a code reader. It then started to run poorly again. Now the codes are for P0305 (cylinder 5 misfire) and P0171 (running lean). Please help.
Thanks for your time.

[kball]

At first I thought you had a bad #5 injector but since you said it ran fine for 30 miles...? You may have to test it and see. The fsm has procedures for this. The P0171 can be the Maf, and O2 sensor, vacuum leak etc... How did you clean your Maf? You didn't rub the actual wires with anything did you? You should only spray maf cleaner or contact cleaner into it and then let it completely dry out.

I'm suspecting if you cleaned the maf correctly and it's okay then maybe you forgot to hook something back up when doing your plugs and you have a vacuum hose unplugged.

[offthahizl]

Maybe I exagerated when I said it ran fine for 30 miles. It ran much better with no vibration noticed. I cleaned the MAF with Maf cleaner without touching the wires. However, one of the screws was striped that attached it to the air duct so I took out the air duct/air filter and sprayed the MAF via the inside of the air duct without actually removing it from the duct. This weekend I will break out the multimeter and test the injectors. Your help is greatly appreciated. Thanks.