Basic info: 1997 3.8 Thunderbird, 190,000 miles
I got this car a month or 2 ago. It's in good shape, especially considering the mileage, but it needs a lot of attention to little problems. It kept throwing codes for lean on both banks (don't remember the numbers), felt like it was choking out under harder acceleration, was down on power across the board, plus there was a weird chugging issue between 1500-2000 rpms that would vary in intensity. I changed out the air and fuel filters, cleaned the MAF (the wires were covered in a fine dust), put in new plugs (Motorcraft OE platinums) and wires (Borg Warner), and changed the EGR valve. The chugging is reduced down to a slight stutter occasionally, the lean codes stayed away, the choking feeling is gone, and power is up from idle to redline.
This morning the lean codes popped back up.
They stayed away for a few weeks, none of the other problems have returned, and it's still running great.
I'm going to clean the MAF again just for kicks. If the codes keep coming back, I'm thinking the fuel pressure regulator is next to be replaced. I don't want to start replacing parts and hope it works though. The stutter appears to be the trans - I'm going to change the fluid and do a Jmod while it's cracked open - so I don't think they are related but not totally sure.
Is there something I'm overlooking here or a common problem with these cars I'm unaware of? Anyone got any ideas?