It's a 05 rx8 first I would die when I put it in neutral then I was going down the road at 5000 rpms and it dropped to 4000 and stayed there for 3 seconds and die it would not start. I have replaced the crankshaft sensor and the fuel pump. It will start if I give it some gas but if I let off of the gas it idle all over the place and dies but if I keep giving it gas it backfires really bad

the fuel pump is an import direct a33078

 

before all this happened
did the car idle normal?
or did you have gas popping and backfires before this?
when was the last time you changed the coil packs?

 

only after I change the coils about 3 months ago

 

you should probably go back and make sure all the spark plug wires are on both the coil packs and spark plugs tight
sometimes they can pop off
also what brand coil packs did you buy?
your car may be back firing because the car is getting unburned gas into the exhaust
that might happen if the spark plugs are not firing

 

the coils look good and so do the wires on both ends and what would cause it to not work without adding gas to it and what elsa would cause it backfire

 

make sure the spark plug wires are on the correct spark plugs
if you crossed the lines that would be bad

why did you replace the crankshaft sensor and fuel pump?
did you have codes before?

most car dealerships charge like 60$ to look at a car, that might be worth it
but they will want to know what parts you changed before the issues started

 

I replaced the crankshaft senor because it was $20 and it wasn't turning over and I replace fuel pump because of the same thing I figured it wasn't the senor but it was cheap and a shot in the dark. It's 150-200 here to have someone to look at it. the wires are connected right