the fact it drives fine then all the sudden drives all crazy makes me think its not a solid mechanical problem like a timing issue but probably something electrical? mike?

 

If the VSS is bad then it will cut spark to the cyclinders to control road speed.
This does not sound like that though.
Does it only do it when driving?
When it acts up if you pull over and shift to park and try to rev the engine what happens?
When it acts up it you shut it off and wait a min and then restart what happens?

 

update

took rover buddy to get the disco on roadside. heres what happened

started right up and drove fine for 3 miles, then backfire and slow lose of power pulled over killed motor let sit for 5 mins. started up and drove fine.... 1 mile later backfireing and lost power hmmm.....

let site for 10 mins.... started up slow slow idle feels like definite fuel starvation! slowly climbed to normal idle drove again just fine 2 miles later backfire and same thing slowly started to loose power. notice now when i turn key to on pos. there is no audible buzzing normally heard from fuel pump.

have buddy stick his head back there and he can hear it but bareley normally is pretty loud as you probably know

im thinking the fuel pump might be dead or close to it does that seem like a fair assumtion any ideas?

 

Yes, good diagnosis, why didnt I thik of that?
You can check the fuel PSI at the fuel rail with a fuel PSI gaguge.

 

Would fuel starvation cause backfiring though?

I'm having sort of a similar problem with my XJ. Mine does it worse when it's cold though, and if you stomp on it, it has all the power in the world. You let off the gas, and it bogs down, starts missing and backfiring. Then it goes away. Some days that's the end of it, some days it comes back. Just depends on how 'Cheep' it wants to be.

Still on the hunt for a Rover. There's a good DI up in Traverse City, MI but apparently, they don't check their email.

 

ill prolly try to work on it tonight im heading up to Nevada to pick up a 71' unimog ahahah it really seems to me its the fuel pump but ill keep posting mike do you have any imput?

 

update!!!

new fuel pump solved it got the proline one from rovers north starts alot better and dosn't act up regained some top end power as well.