Not Enough Boost

[Laredo GN]

I have a 1985 GN with Ported&Polished heads, 3 inch Up/Down pipe, 2800 stall, 390 Gears/Adjustable Fuel Pressure Regulator, 3 inch exhaust with Flowmasters, Blue Tip Injectors, Enhanced Turbo, Cold Air Pipe & 18 Inch K&N a 93 Octane ship from Poston(NO SCAN TOOL). I have the following problem: I can build boost when the car is cold, but not when it's hot, the car builds up boost and it takes off screaming but it shows that is building boost (16 PSI's) but it does not feel like they are 16 PSI's (the car is going nowhere) because it feels like is BOGGING DOWN real bad in first gear, and when second gear comes on it takes off but again it is very slow on first and it was not like that the day before (very strong first & second). There are no leaks on the exhaust or the Up/Down pipes, the vehicle has been recently overhauled with the Postons High Performance Kit (About 4, 000 Miles ago), Any help up there from you guys that know please give me some things to look for. THANK-YOU

TOYS: 2002 True Blue Lightning
1970 Plymouth GTX 440 Six Pack
1993 Z28 several bolt ons
1969 Roadrunner 510 CU