stumble when accelerating hard at low gears

[keelhaul]

hello.

got my new car now, i drove it 880 miles over the mountains, and it was so awesome.
but when im accelerating the engine stumbles a bit when i floor it in a low gear and want to activate the turbo. this stumbling is never the same, and sometimes its not stumbling at all.

when it starts to stumble, i can release the gas pedal a bit and the stumble stops, and then i can give more gas, and its not sure if it will stumble again. thats boring

so what can this be? vacuum leak? plugs? clogged air intake? i have no idea
i think the turbo is working, it was extremely nice to drive on highways and i could go up to 110 miles speed pretty fast, and im sure it had more to give, but couldnt go faster cuz of the road. im very satisfied with the car. pics will come. i have a turbo bar-gauge too, if info from that can help.

so it stumbles sometimes when i floor it. any inputs?

91 legacy stock turbo ej20g

[ericem]

Have you done a tune up on it? new spark plugs (stick to ngk) wires (stick to oem or ngk) air filter, fuel filter, pcv valve??

[keelhaul]

no, i havent tuned it up yet.

i will buy the stuff needed and get it on. looks like i must tear down a lot on this engine to get to the spark plugs its not like my ej18 stock on the other car, hehe. this car has a lot of stuff under the hood. will be interesting.

im running octane 95 gas, should i buy octane 98 gas, or is 95 enough for 200hp?