97 gmc 1500

I'm having a few problems with my 97 gmc 1500 5.7.My first problem is after having the intake manifold gasket replaced my truck started to miss slightly.So i changed the plugs,Wires,and rotor.But it still has that miss.Only thing left is the cap and coil to replaced or maybe the injectors wich i don't won't to mess with.I've been running chervon gas hoping it might help it.Now a month later it don't won't to start on the first crank sometimes it has to be cranked twice to get it to start.The brakes have always sucked on this truck but now it feels i like i'm hauling a heavy load when i go to stop like its pushing the truck forward.I don't know if that makes any sense but thats what it feels like to me.I was thinking maybe the brake booster might be going out..Don't really feel like replacing everything til i find the problems since i replaced the wires that were $70.00 and didn't cure the problem.So any help would be great.Thankz..

you need to step back..back to square one first
who did the manifold gasket...need to check and recheck that first...make sure no vac leaks around manifold...gasket not installed backwards or upside down...factory gasket kit?? SES ligt coming on? which cylinder is picking up missfire?
brakes:: the brakes on the older body style were a little undersized....more so only on suv's
make sure rears are adjusted correctly...wheel cylinders not leaking on rear shoes....what kinda of frt pads-aftermarket are ok if there good quality

When does it misfire? During heavy acceleration or light load cruise(50 mph on level ground)? Or all the time? It does sound like an intake leak

I found the problem with the brakes was the wheel cylinder on the driverside was leaking Just like you said PK55Z85.The brakes are factory and the truck has 113,000..I will be replacing brake pads,shoes, wheel cylinder and bleeding the brakes...Does anybody know a good brand of brakes besides the cheap lifetime that most auto stores carry?The manifold gasket was done by Chevrolet dealership.I have no idea if they put the gasket on backwards or upside down.There is no lights on but i took it to autozone had them do a trouble code and they said there it no code stored but they said the check engine should be on but it isn't.I don't know which cylinder is misfiring and i only notice it when idling watching the the rpm gauge and can feel it through the steering wheel but, when driving don't really notice it. It has been burning more gas then normal..I will take it back to chevrolet and have them pressure test to see the gasket is leaking.It cost $647.95 for the gasket to be fixed so if that is the problem they better fix it.Thankz PK55Z85 and Jeremy for your help...

GMC1500.....your chevy dealer should be more than willing to recheck their work...if not ask for the svr mgr....at the very least they should diagnosis the problem for you at no charge...just keep in mind...their always could be the chance you may somthing not related to the work that was
preformed. also keep in mind you'll get a better response from them at first by being "nice" about it.
brakes...i would stay away from most aftermarket brake linings...unless you use some type of higher performance type brakes pads/shoes...just keep in mind they may be made out of a harder compound...which would result in more brake noise "brake metalic squeak".. factory/ac-delco pads/shoes are pretty good and do last longer than most standard aftermarket linings.

check your compression.

PK55Z85... I have'nt had time to take my truck back to Chevrolet.I agree about being nice about it bc it might not be my problem.I think i will get some ac delco brakes like you said since the factory ones lasted this long and stay away from the aftermarket ones.Thankz