s10 problems

I have a 91 s10 and there is a couple of things wrong. Frist off when u try to crank it over it takes about 4 to 5 times of turning it over for it to start. I hae even turn the key on for a min to see if the fuel pump takes a min and that dont help.. the other problem is that there is oil all over my air filter. and i just put one on there about a month ago. can somebody tell me why im getting oil in my air filter? could this also have somthing to do with the truck not strating up right.. another thing is that when im driving down the road and i wait a min to shift the truck seems to have a lil boost to it once it hits a high rpm. kinda like a turbo or something? if anybody has any ideas that would be great thanks....:banghead:

oh yeah the truck has a 2.5 tbi and is a 5 speed.

How is the tune up end?
Good Ac delco plugs and wires and fuel filter?
Good hot blue spark?
Have you got good fuel pressure?
Also check the back pressure on exhaust system.
How is the pcv valve and engine breather system?
Any codes or check engine lights?