The engine keeps jumping!!!

Hey there guys, i keep having this problem when i hit the gas slowly where its about from 1500 to 2500 rpm the car kind of jump and shake the hell out of me, i change the fuel pump today with the fuel filter but still its the same... Any ideas why???
Injectors maybe???
I have m20b20 which recently made it to m20b23
Oh and one more thing, when the engine gets to the right tem and the rpm goes to 800 it kind of starts playing up and down, its not stable most of the times

when you made it a b23, howd you go about doing it?

Originally Posted by downhiller

when you made it a b23, howd you go about doing it?

I changed the crankshaft n the pistons like it says on the forums, a lot of people did that!!!
Anyways this problem was before i fixed the engine

did you do anything else, like bore the walls, shave the head, rebuild the head, replacing timing chain/belt, vacuum tubing, intake boot, ect.

it sounds like a power balance issue, so anything from poor injector flow to a vacuum leak to weak spark.

Originally Posted by downhiller

did you do anything else, like bore the walls, shave the head, rebuild the head, replacing timing chain/belt, vacuum tubing, intake boot, ect.

it sounds like a power balance issue, so anything from poor injector flow to a vacuum leak to weak spark.

Well today in the morning it kept turning off when i stop at the stop light and after like 20 min its all gone and working perfectly, i think its the spark plugs or there cables, im gonna buy new spark plugs tomorrow and see what happens