Compression Question//Head Gaskets

Okay, Kinda new at this guys, but im doing a head gasket change on a 87 5.0 the engine is tweaked out, with vortech blower msd, exhuast, heads, etc.. the commons n such.. well.. before i noticed the gaskets on the heads were bad, i was noticing a chug, or seemed like misses, if i took the car up to about 2500 rpms, and when i would stop at lights and such, sometimes it would start to rev down to like 300 or so, and jump up to like 1100 or so, i have a
E303 cam but i never did that.. could that of been the gaskets going bad causin compression to mess up? Any replys would be most appreciated thanx guys...

Thanx, i checked that website out and im gonna follow that procedure, as for the "missin" the weird thing is tho, once i changed my plugs and finally got the gap about as close to perfect as possible it went away for awhile.. but then came back again.. carbon build up? As for the blower, pulls like 7 to 10 psi timin shouldnt be bad on it.. carbon build up might be a issue tho i have to deal with.. Any ideas on where i can find all the gaskets im gonna have to replace and what brand i should go with? I need some heavy duty ones so no cheap o's. Thanx for the reply tho

Reply to the timing

Okay i do have a Boost Retard, Its just alil box with a knob i can turn.. problem is, i only have 0 1 2 3 and 4.. usually sits right above 1 at like 1100 or 1200.. i dont ever notice a difference when i turn the knob tho.. so 8 is way out of the question.. What im stuck on now trying to change head gaskets is trying to get the lower manifold off.. its a edlebrok mani, pretty common one for mustangs ive been seein.. there is a plug i think in the back of it on the driver's side.. i took that plug off and under it was lots of anti freeze, that common? BTW Im only 20, haha and this is the first big project ive done on a engine before, So i have many questions. Since im going to Wyotech it would make sense to start now with learning about my engine. Im also afraid of taking the springs, rocker arms and stuff off, because im not sure how exactly they go back on.. So any websites or manuals or anything would be very helpful with all that... Cant think of anything else right now to say.. but keep the replys coming please.. Thanx