95 OMC 5.8L runs but wont idle, (surges)

[puckett27]

Hello, new here. I had a customer bring me his boat, its a 95 chris craft and it has a OMC COBRA 5.8L manufactured by Volvo penta model # 58faphue. it ran great last year and I winterized it for him. He dropped it off this year for me to get it ready and it would crank but it wouldn't take off. and the fuel pump wouldn't work either and had no spark. I took the spout out and it would spark then, but the fuel pump still wouldn't work. checked the kill switch system and ignition system, and figured the ECM Module was bad. changed it and it runs great but wont idle now. It idles rough and up and down, and when you come off of wide open throttle it shuts off. I replaced the MAP sensor and the Idle control valve on the throttle body, and clean the throttle body, replaced sparkplugs, checked timing with the spout out, and changed the fuel filter. I don't know where to go from here! any help would be great. I'm wondering if the new computer is bad. Thank you for any help!!