Backfires/hesitates, then acts normal for several sec. after sitting?

i asked about this last tuesday when it originally happened.

i went to the gas station, shut the car off and started it back up and it started. the car will backfire/pop and hesitate and accelerates slowly. there are certain points in the rpm/pedal where it will go smoothly or stop popping as bad.

i limped it to my cousins house, popped the hood, checked all my plug wires, ect. then i started it back up after about 10 minutes and went for a short drive. in first and second gear it was fine, then it started in third again.

it had done it once before and we replaced the fuel filter and it went away. so we went and bought a fuel filter, installed it. then i started it up after probably an hour and it was fine down his street through third gear. then taking off in first gear from the stop sign it started.

we checked timing, plugs new, new cap/rotor, new fule filter, ect.

my car is still down waiting for the new injectors i ordered. we took off my old intake since i was installing a cobra, and there is alot of dirt inside the engine. the filter on my car was dirty when i got it, its a K&N so i cleaned it and never did anything since. well there is alot of dirt in the speed density inlet tube, egr spacer, throttle body, and intake, ect. before taking it apart we thought it was the injectors, with that and finding this dirt can i pretty much conclude it has to due with them?

i checked all my vacuum lines prior to taking old intake off, and they were all fine. this is my daily driver, and its been a real pita getting to school the past week without car. tomorrow my injectors are supposed to be here, if they dont work, what else is there i can check?

id like to get some things i can check before hand just incase it still isint running right tomorrow.

stock injectors are being replaced with bosch 4-way, intake is being replaced with cobra, tb is going to 70mm, and im replacing speed density with mass air/80mm mam on tuesday.

does it sound like injectors after finding the dirt? any similar experiences? thanks

it was coming from the engine area, trying to get through the city with it running like it was i wasn't really paying all that much attention.

also it would rev fine without any of it, just when the car was in gear it does it.

cousin and i looked at it, and after checking everything we thought it was injectors since they had 100k, engine is dirty, sometimes its will run smoother depending on amount of throttle, and before i had a similar problem and it was fuel related (filter). so we think the injectors are dirty and arent spraying right.

dont have a way to run any codes.

i have new injectors in the mail. im hoping that fixes it, but if for some reason it doesn't i might end up taking it somewhere.

does this distinctly sound like anything?

that is the one other thing my cousin had mentioned. he had 3 of them go out though, and each time he got no warning. so we kind of dis-reguarded that.

just trying to avoid dropping the tank

really? cousin made it sound much worse then that. reguardless, if it goes to that its another $100