Different Cam?

Lately I have been having a problem with accerlation under full throttle. Normal driving is fine and on the highway accerlation is fine. This just happens at a stop. I am only getting 10" at idle when in drive but goes up to 15" when in park. The car is strugging to get to 3K but once its there the car throws you back into the seat. The heads that are on the car are stage 3 ported and polished when I bought them there was a reciept for about 1000 worth of machine work. The previous owner had a custom cam but didn't want to sell it. I was told that the stock cam would be ok. Car is acting like there is a vaccum leak but can't find one. Just wanted to get some other opinions if it might need a different cam because of the higher flow rate of the heads or if I need to search harder for a leak. Thanks for the help.

It has the stock cam now and I can't remember the shop but the ports were opened to the max. The heads are the old style twisted wedge heads.

I did notice that when I tried adjusting the idle speed when the idle was up in the 1k-1500 range the vaccum was pulling 15-20.

I checked voltage on TPS and noticed that was at .7 then noticed that the screw on the bottom the throttle was backing out. Got a longer screw and nut to lock it in place adjusted my base idle to around 750 (best guess using stock tach) and then adjusted TPS to 0.98 on my meter. Also read somewhere that if the charcoal canister is bad that it can cause a leak along with the purge valve. So replaced the valve and canister. Doing the above listed the vaccum went to 12" both still runs the same. Ran codes and got 67 koeo which is because I bypassed the safety switch instead of dropping the tranny to get to broken wire. Tried running the koer code, the engine revved like normal but code reader did flash to say it was V8 and then no codes. Tried that two times with no luck. I noticed that there was some oil leaking from the valve cover gasket on pass. side could that be causing an idle vacuum.