Hey guys after I got the timing fixed(the crank key was broke and set itself off about 20 degrees) and drove it a few hundred miles everything seemed ok running good then it started dieing
at stoplights every so often then the prefomance started lacking, everyday it seemed to get a little worse so had to pump the
gas one morning to get it to start. I ran the OBD. Got the codes first one was 131 (o2 voltage low bank #1 ) 2nd was 400
(egr flow malfuction) 3rd was 131 again then #4 was 171 system too lean bank #1 then 5th was egr again.
When it is cold start up it got no power I must let it warm up 10-15 min then it gets better the longer you drive it. but it has
power surges most of the time.
and stll lacks alot of power at the low end at take off
I checked the egr it was a little loose I took it off and it was pretty clean no build up. checked the diaphram its working ok.
Cleared all the codes reinstalled egr still no better. Egr working fine no clogs ect. No vacumm leaks
all air valves /sensors seem to be operating as per checks in the Haynes and Chiltons.
Now engine light back on and getting a PO505 which is idle control system malfunction and a PO131 which is a o2 circuit low voltage bank 1 and a pending code of PO 171 which is system too lean bank 1. Any Ideas out there before I have to take it in to the shop.?

I had the same problem, I went through 2 sets of plug wires, cap rotor, ignition timing checks, timing belt checks....everything under the sun. I never tried to pull any codes though. So in a last ditch effort i hollowed out my cat. Problem solved..... Don't know if this will help you.

any update on this??? ive been abUSING the search for anything on this lean topic, mine has started to run lean according to my plugs, and also is starting the surging every once and awhile...and i dont know what to do....i swapped almost everything on the motor within the last year or so when she got rebuilt...anyone know a direction to point me in?? the 1 thing off hand that i can thin k of that wasnt changed was the fuel pressure regulator, would this be a good thing to start off with changing??

thanks in advance, Justin

How did you fix the broken key? Mine had this and I had to fill it in with JB weld, get a new pully and red lock tight a new crank bolt on. To me, if you don't address the issue of the crank bolt backing out it will be a recurring problem. I have 10K on my JB Weld...

Start with the EGR, if its sticking open then you will get lean readings.

i put a new valve on it and completely cleaned out all the passages for the egr as well when the motor was out about 6000 miles ago...the egr seems to be ok, im guessing...

a damn good link, but it runs excellent during warm up and once warm...so all of that stuff has to be working properly, it idles up to around 13-1400 r's and idles at 750 all day long while warm...and it also starts fine agin once cold, or even once its warm and i restart it...this has me baffled...not really a problem whatsoever but kinda irritating to say the least, what really has me baffled is that it can sit for the same time period during the day and fire right up, but when it sits overnight is the only time it does it???

The EGR system is so complex its stupid.  First, i would figure out if the EGR valve is functioning properly, need a vacuum tool to test it, then see if you have a vacuum leak somewhere, that would explain the lean condition.  Although, with a lean condition on just a few bank may suggest a valve problem, and being that the crank pulley wasn't right for a little while, it would make sense.  Anyways, link to complete troubleshooting procedures... its a pain.  Also, don't overlook the EGR vacuum regulator valve and the EGR temp sensor, they could be the culprit.

http://carfix.stufftoread.com/EGR.html

also damn good link!!! but i recently replaced the fuel pressure reg. and its BEAUTIFUL now..purrs away like a kitten!