I've got a 1995 T100 v6 SR5 A/T 4x4 and I've had it for about a year. Recently it's been stricken with a disease that I am having a terrible time trying to diagnose. The problems it's having is hesitation and stalling, mostly upon startup or short distances. On a cold start, it'll start up relatively quick and run smoothly for a short time. The last time I tried to drive it, I barely got off my street when it started acting up. It would just start sputtering heavily once I try to get up to driving speed and then just conk out on me mid drive. Luckily I've been able to limp home safely each time, and when I say limp, I mean a few things. First and foremost is an increased cranking time (cranks normally just needs a good 5-10 seconds before it actually fires up) and then when it does start, it's very very sporadic, stalling almost instantly. Next is the hesitation and stalling. If I'm lucky enough to actually get it in gear and try to drive, I can push the gas pedal and get almost no acceleration, but enough to get it home very slowly (I'm positive the issue is not in the transmission). On on occasion, I was driving about 35mph on a straight road then all of a sudden the problem came back alive. I heard it putter a few times and watched my RPM gauge drop and jump back up quickly a few times then when I slowed to a stop at a red light, it cut off altogether.
With it on and the hood up, I was only able to replicate the problem when I open the throttle quickly and let go and then open it again slowly. Sometimes I could open it slowly and replicate the issue. When it was doing this, it almost felt like multiple cylinders would misfire, stumbling very hard and then dying when I let go of throttle. Today I was out there trying again and was noticing I could turn it on and give it gas and it would rev just fine for the most part, but when it got up to 2200rpm that's when the stuttering started. At 2200rpm it would stutter about once per second. If I tried to get it up to about 2500rpm, it would stutter about 3-4 times each second. When I released the gas, it would go down to idle and stay there.

Some things to know about this truck...

• The idle has been low pretty much the whole time I've had the truck, about 600-650rpm.
• Driving normally, when I go to accelerate from a stop, it's always had a momentary, almost unnoticeable hiccup at the beginning of acceleration.
• I've replaced the MAF when the problem started, and for a few days it was driving great! But the problem persisted after about 50 miles
• This truck does NOT have an EGR valve or MAP sensor

A few weeks after I got the truck, my brake pedal went hard. At first I thought booster (obviously) but after some testing, I started to lean towards an internally leaking master cylinder. When I press the brake pedal, it would get harder during its normal travel but I'd have to get all the way down the pedal travel to get any braking action whatsoever and would have to press EVEN further if I'm going to stop the truck in time. Needless to say, I now have a very strong right leg. I recently replaced the master cylinder, but on my test drive, the problem still occurred. So now I'm starting to think I've got a heavy vacuum leak and it's related to my engine problem.
With that being said, I do believe the engine problem lies with vacuum leak rather than spark or fuel, however I'm not ruling them out entirely.

Any help would be greatly appreciated. I don't believe I mentioned everything but will edit the post as soon as I do remember.
I'm going to be starting a new job soon and I'll be able to actually spend money on replacement parts soon too. Thank you in advance!