ill try to start it and it will sit there and crank and crank but wont start then i try to start it again and give it some gas and it was turn on to like 100rpm then turn off and the third time it will turn on to 500rpms then go down but if i give it gas it will go to normal my guess is fuel pump but idk any suggestions

 

Have you tested fuel pressure? Why guess?

 

Checking your fuel pressure is a good step.

But the first, quickest, and cheapest thing for you to check is the condition of your battery, battery posts, clamps, cables, and ground connections. Provided the battery is in good shape, the connections must be clean, shiny, tight, and free of corrosion.

Don't trust what these connections look like from the outside, disconnect them, inspect, and clean them. Inside they can be quite corroded without showing my concern on the outside.

What you are describing sounds a lot like a start with a low voltage or poor ground problem. Which is usually a connection/cable problem, a battery problem, or an alternator problem. (the first one being the most common). Someone on here or JF once described the technical reason why that strange low rpm, gas required, running condition occurs, but I do not recall the exact details. Something to do with the ECU not being happy and going into a safety or "reboot" type condition.

I have had the exact symptoms you describe when troubleshooting my own starting problems, and it was resolved by cleaning the battery clamps, ground connections, and battery posts. (disconnect, wire brush until shiny, reconnect tightly. Battery posts and clamps should be shiny, clean, and tight).