96 lumina p1200 bucking jerking highway speeds

I have a 96 lumina it was in need of a tune up so I out in new wires and plugs and it seemed to run fine but about a week later it started bucking and jerking at highway speeds. I could get it to stop by either giving it more gas or by lettng off the gas. Also the service engine soon light would flash at different times. I checked the codes and got a p1200 local gm dealer had never heard of this thought it might be a computer but I dont believe him.

Anyway I tested the injectors they all read at about 12.2 ohms and none of them leaked when I turned the key on. So I put it back together In the process of putting it back together I got confused as toi which cylinder is number one is it in the front of the engine or the back of the engine. I would really like some help on this problem.

P.S. there was also gas and water in the oil.

ryan

Im sorry this is the 3.4 sfi
ryan

Wait..gas AND water in the oil?

Cylinder location is the same for the 3.1

Standing at the front of the car, look towards the rear.

3.1 V6, the order is:
Firewall, left to right
1 3 5
2 4 6
Radiator, left to right
Coil packs are, left to right, 1/4, 6/3, 2/5

I don't have The Book with me right now for the DTC, but if a GM dealer hasn't heard of it, make sure you wrote the code down right.

Yes there was gas and water in the oil. there wasnt very much water in the oil but there was some. The mechanic at the dealer had never heard of it. That doesnt mean it doesnt exist. it was p1200.

P1200 - Injector control Circuit

Gas in your oil usually points to your injectors. Water in your oil- when was the last time your lower intake gasket was replaced? May be cracked, contaminating your oil. Even though you've already tested the resistance values for your injectors, and put in new spark plugs, check your plugs again. The dirtier plug/plugs will point to the problem injectors if it is only the injectors themselves. Injector control circuit could point to the ecm.
Autozone.com has a repair info section, that lists trouble codes for most cars:

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/repair_info/repair_info.jsp

I havent ever replaced the lower intake manifold gasket. I got the car at 100000miles and now it has 200000 on it. Do they go out often.

The other thing that I remember happening earlier this summer is that the fuel pump relay would click and the car wouldnt start. At that time I replaced the fuel pump and the relay itself that didnt fix the problem but it just quit on its own. I have no I dea if this is related or not.
Thanks for your input

That lower intake is probably already gone on you. From factory, I went 71,480somethin before I noticed my coolant was disappearing somewhere. I'm not sure how long the replacement gaskets from FelPro last, but if you got it at 100k and drove it another 100k, its more than likely gone out already. Losing coolant anywheres?

there is some coolant that drips off the a/c compressor. I changed the water because of this but that wasnt the problem there is some coolant on the side of the head but cant tell where it is coming from almost has to be that gasket or the head gasket.

Intake manifold gaskets are an issue with most W-body cars. That coolant coming from the side of the head is most likely the manifold gasket leaking. To partially rule out head gasket failure, check your oil. Does it look like a chocolate milk shake? If not, it may not be your head gasket.

Yes there was water in the oil.