2000 explorer xlt wont start unless i hold the gas wide open

[tacoma man.]

what could be wrong? my mom has a 2000 explorer
4.0 sohc, auto, when we try to start it up
it just cranks. so i held the gas wide open and it
fired up but chugged and missed then died. several
places are saying the timing chain needs replaced.
it will cost her hundreds to do that. im thinking it has
something to do with the air and fuel mixture.

[XLT03]

Double check alll of the vaccum lines especially the ones on a tree driver side near firewall. There should be 4 vac. lines going there. There may also be one that is capped with a rubber cap. Make sure that they are all on.

[tacoma man.]

i just got in from checking it had the whole air
intake off and found that the "i guess air/idle"
screw was backed out on the throttle body.
i tightened the screw and the motor starts
as soon as the key is turned over. so that problem
is fixed thanks for your help.