Help...fresh built 355 "dieseling" or running on...

[1970witha355]

Ok heres what i have. The block is a 1975 350. It is bored 30 over. It has flat top pistons. The block has been decked to zero (the pistons come up level with the block). It has stock iron "441" heads with 194/150 valves. The cam is an isky "201SL1". This is a circle track cam im told. The specs are: 390/410 lift, 228/232 duration @ 50, and a 108 lobe seperation, 2000-6500 rpm range. I dont know what the compression would be, im guessing around 10:1. I am running 87 octane gas. I have a TH400 tranny with stock (1300)rpm converter. The problem is the engine should be making 300hp give or take. It sure doesnt feel like it. I should be able to floor it and rip the truck sideways. It feels weaker than an old worn out stock inline 6. It doesnt feel like the 4 barrel is opening (new edelbrock carb). When I shut the truck off, it stumbles for a second or "deisels" then shuts off. The timing is set at 10 btdc. WTF!!!!!!!!!!!! I am so frustrated that I am sick! Is the answer better gas, stall converter, NEW ENGINE???????????? OH MAN AM I PISSED! HELP HELP HELP!!!!!!!!!!