need help with my 2000!

[cruiser5001]

2000 bonneville needing help

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Hi, I hope I am in the right place to post this. I am having problems with my 2000 bonnevile 3800 non supercharged with 200,000 miles on it. I bought it in 2002 and it's always been a reliable car. usually it runs great until last week and need some input as to what I should do.
here is what I have done to the car recently. new plenum gasket, valve cover gaskets, new axle bearings front and rear, new cv half shafts right and left, new rotors, brakes, calipers, new tps sensor, new coils, spark plugs and wires.
now the problems that have started since I did all the work. getting codes p0418, p0201,
p0300. at first I was showing the 418 code only and ended up taking it to firestone after I changed the relay and they couldn't figure it out and said it was in the computer. while it was there I had them do a brake fluid change for me since everything else was new with the brakes. then a couple days later the headlights would turn off and on at random. then the abs light and the brake light would come on at random (usually after hitting a bump) so I checked all connections again they were all tight.
2 days ago I started it and the engine had a miss. hooked up the scan tool and the p0201 and p0300 codes came up. I checked the injectors with a ohm meter they all read 12.5 ohms so I'm thinking that is fine.
so I guess now I am wondering if I really do need a computer or maybe it's just some kind of a short. I have about tapped out on the money I was going to spend on it and didn't want to get a computer without another opinion. at this point I may be overthinking the problem.
thank you for reading this far and for any comments I recieve......

[leatherneck]

First thing I would check is the grounding busses. there are 2 I am aware of under teh hood, one on the engine next to the Ignition coil packs bolted to the head. and then one on top of the transmission just under the throttle body. Make sure they are tight.

I had alot of intermittant issues and the one on the transmission was just loose enough to cause codes to pop up.

[cruiser5001]

thanks for the advice! now that you have brought it up it really does sound like a grounding issue. I'll be on it first thing this morning. thank you. I'll let you know how it goes......

[cruiser5001]

ok here is what happened. I cleaned all the grounds I could find and a couple of them really needed it. I started the car and it was running perfectly, no misses and the only code was the p0418 for the air pump relay. so it ran fine for about 10 minutes put the fuse box cover back on under the hood so I could test drive it and it started to miss again. so I kinda shook the fuse box and the motor died altogether. turned the key and not even a light would come on! so I disconnected the negetive battery cable then the battery cable at the fuse box and lifted the fuse box up and pushed all the connectors all the way on. a couple of them were pretty loose.
that did the trick. I drove it around for about 50 miles and had no codes at all and the abs brakes worked perfectly!
I wanted to thank you for pointing me it the right direction, it led me to the actual problem. been messing with this thing for a week now! was ready to pull my hair out. LOL

thanks again!
Roger

[leatherneck]

Awesome.. So instead of it ground side it was supply side Great that its running well for you now. At least it was relatively simple, some electrical can be a real pain.

[cruiser5001]

thank you. yeah it was a real pain to figure it out but easy to fix. I guess after 11 years of hitting holes they worked loose somehow. I have never seen this happen before. sure beats buying a new computer! LOL.