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Hi I'm new to this forum I have a 1988 dodge d150 with tbi stock 318 and I have been fighting with it for a month replaced head gaskets on it put it back together had started it had vacuum leak found that then it ran fine for a few days ran out of gas started it backfiring again changed injectors ran like new cut it off wouldn't start back change throttle sensor started running rich but started drove it no back fires oil light was on after the new oil and filter I put in so changed the sensor oil light went off but now it's back to running lean its like it switches back and forth from lean to rich and when it's idling it seem fine I give it gas it bogs at first the after I let it off it bogs the returns to normal idle please and advice would be appreciated

 

Try disconnecting the front O2 sensor (I think you only have one....) and see if it runs better.

 

Okay I will try that in the morning it's on the passenger side ain't it

 

Think so....

 

I checked it seemed like it was good but I put vacuum guage on it and reads good at idle but drops to 15 or 14 when I put into gear

 

I don't think that's normal.... no reason vacuum should fall off like that that I am aware of..... Might wanna check timing chain slop....

 

Would timing chain let it run rich to lean back and forths like it is ?

 

Nope. Valve timing won't have much, if any, effect on mixture ratio.

 

That's what has me stuck the vacuum reads perfect till I put it in gear then it will run fine and have no problems then go to start it back up and it will start back firing

 

Something is getting hot, and failing......