97 Bonneville DTC P0171 frustration! Help!!!

[Bumpy5]

I have a 1997 Bonneville. I have had a check engine light on for some time now. My problems use to be that the car would run rough, had poor acceleration and, after running for about 30-60 minutes, it would not restart (after sitting for about 10-20 minutes). I scanned for codes and had a P0171 fuel system lean bank 1 code and occasionally a P0301 cyl 1 misfire code. A few times (when it started crappy) I would see an occasional P0305 (cyl 5 misfire) or a P0300 (random cyl misfre) code. Didn't bother me too much on the running issue, but hated the "no restart" issue. My problem became BIG when my plates expired and by Illinois law, I have to pass an emissions test before I can renew my plates (exp 2/09).

Since then I have replaced the following parts (in no small parts on the advise of several GM techs)...

The lower intake gaskets, upper intake manifold assembly, all 6 injectors, checked and fixed ALL vacume leaks, replaced the MAP sensor, plugs, wires, all 3 coils. Now it runs smoother but I still get the P0171 code immediately after start up.

Now today... I was following a diagnostic chart from ALLDATA and it led me to check the Mass Air Flow sensor. I just left work and figured I would check into it further once I got home. I made a 10 minute stop, on the way home, and when I came back to my car it would not start. So based on what I had read in the ALLDATA info, I decided to unplug the MAF and try starting it, thinking false signals from the MAF were causing a flooding issue (not sure). It started right up! So then I decided to leave it unplugged until I got home. The car drove like gangbusters!!! I can't remember the last time it had that much power & torque. But all good things must come to an end, right? Half way home the car just died. I waited about 1 minute and it restarted. I thought it had something to do with the MAF being unplugged and figured I better plug it back in. It seemed to me that the MAF sensor was my problem because once it was plugged back in I had poor acceleration and it would bogg on hard accel. I replaced the MAF as soon as I got home, cleared the codes, and decided to drive it (and chance the ticket for expired plates) through a drive pattern to complete the SRTs. I drove it, with my scanner attached, for about an hour (through various speeds) and after I stopped and let it idle for about 3 minutes, all systems were complete. So I thought I was in the clear! On the way back home (25 miles away) I was going about 60-65 mph and out of nowhere, the car jerked! Like it shut off and back on in a second. I looked at the scanned and it showed "communication error." After that I babied the car back to the house for fear that It would shut off and maybe NOT restart the next time. Once at home I left the car running and rechecked for codes. Of course the P0171 was there, but now along with "my buddy" the P0301 misfire code.

I am sooo lost and sooo broke! Does anyone have ANY ideas of what might be giving me all this grief? I really need to solve this and pass an emissions test so I can legalize my vehicle again!

[maxwedge]

Welcome to AF. Wow lotsa of stuff done here, but did you ever check fuel pressure, also when it won't start do you have spark and/or injector pulse?