215k miles, 93 245

I've looked for air intake hose leaks, replaced the O2 sensor and fuel pressure regulator, and checked the fuses. I've cleaned the throttle body and idle air valve with cleaner and tightened all the hoses.

The engine sputters a bit when first accelerating from a stop, then drives fine. After about 4 or 5 days of this, the Check Engine Light (CEL) comes on. Picked up two codes related to Excessive lean/rich mixture at idle and cruise. I'm thinking the intake manifold gasket is the problem?

After disconnecting the battery (to reset the computer), the CEL stays off for 4 or 5 days and comes right back in. Once the CEL comes in, the symptom disappears. I could drive the car fine indefinately with the CEL illuminated (because the sputtering goes away), but I don't like having the CEL on.

I've posted this problem a couple of times before and received all the suggestions that I listed in the first sentence, but nothing has helped. I'm about ready to take her in to the repair shop to find the root cause..but I just wanted to pulse the brickboard again to see if anyone can help.

Thanks,
Cabbie