The car hasnt been started in 3 years.what should i do to get it running?

Probably complete failure of the I/P dimmer

you could try to reset oil soon change light. like you should do every time you change oil. If so equip

if the carb has set for as long as well you will proubly have to rebuild it

1) Disconnect your positive terminal (Warning don't allow terminals to
Touch.)
2) Go to fuse box Remove the ECM fuse (leave fuse out for 10 minutes)
3) Put fuse back in its slot, the connect the terminal.

It is high time to see that your car had a decent maintenance done on it as it has served you 110K miles. Please get this necessary schedules of work done with replacement so that it will continue to give you many more years of service.
Some tips for poor start and performance.

http://www.fixya.com/cars/r5843031-tips_check_car_not_start

your fuel pump has probably seized if it hasnt been ran for two years

it has to relearn the idle it may take about 40mins of driving to do this

its probly due to being stood bump start the truck this shud release the pressure plate on the clutch then it will release bump it in 4th gear if manual if auto then start it up it shud release then hope this helps

not familiar with immobiliser. i would check connections between ignition switch and starter relay and connections between starter relay and starter, in other words that whole starter circuit. some of the connections may be weak where they go to power or ground. new battery makes it work okay, then it after while not so good makes me suspect those connections. it could also be a starter problem, might be a burnt place on the starter, when the starter motor stops in a certain place it can't get good connection and so won't let current pass, motor can't turn, no start. hope this helps.

I had the same problem and dealt with it over a year no one could figure it out, after 3 mechanics looked at it, a mechanic fixed the fuel pump and it hasnt done it in 2 years...