Engine issues

Hello, I have searched around for the past couple days on the site to find an answer to my issue to no avail. I have a 95 chev c1500 with a 350. Everything has been running well and been getting great fuel mileage until recently. In the mornings I fire her up with out an issue and soon and I touch the brakes to put it in gear RPMS drop, stalls out for a second, RPMS jump back up and is running. Then after that I'm basically coasting down the end of the street to the stop sign ( maybe a 100 yards so no use putting foot into it), during this it sounds like my truck is bored and cammed ( almost like if the truck was a 383 or a -40 cold start) I get to the stop sign and then I accelerate up to 50km/hr for a couple blocks. After the yield sign it seems like it won't kick down, RPMS are around 1000, but I constantly have to tap or lightly ride the brakes to keep it from gaining speed. Like I said seems like it won't kick down. I've gone through and checked for vacuum leaks, stuck cables etc. Not really wanting to throw bunch of parts at it just for fun. The other thing is that it seems to be burning more fuel than normal, sometimes it does smell a little rich. After getting up to operating temp and driving for least 10 mins, if I pull over and put it into park and let idle after a couple mins the check engine light comes on. Not sure if all of this is related, or everything is starting to pop up at once. Engine has 287,000 kms on it.
I did throw a new cap and rotor in over the weekend because I always have a spare kicking around
Air filter is new
Oil is changed very regularly
Plugs and wires replaced 25,000 kms ago ( I did pull couple plugs out and check gaps, everything is good)
Fuel filter was done under 15,000 kms ago
I have a couple ideas what it may be, but like I said earlier I don't want to just start throwing new parts on for fun.
Sorry for the long post, and thanks for the info I hopefully will receive.

I'm not very well versed in the the small blocks of this era, however my 2000 K3500 with a 7.4L has about the same miles on it and had a similar issue. Mine was solved with new injectors and fuel pressure regulator. I cannot remember if the '95 was still TBI or if it was the Vortec MPI with the spider injectors, but regardless, injector issues could be your culprit. It could be that your'e getting so much fuel at start up that it wants to stall at first and then once you get going keeps your RPM's high. Your CEL is probably being thrown by the O2 sensors detecting the high doses of unburned fuel. If your truck is the TBI the easiest way to check for fuel injector issues is to pull the air cleaner cover off and start and run it for a few minutes. Check the spray pattern your injectors are throwing. Should be misting fuel. If you're getting drops or if you see gas pooled up in the bottom of the intake manifold there is your answer, and should account for the worse milage. If you have the vortec then probably the best bet is to start with a fuel pressure leakdown test and go from there.

Thanks Tom for your reply. Does make sense and wasn't something I was leaning towards. That could be the culprit yet it doesn't explain the non kick down. I drove it at lunch and was acting up, dropped down to 2nd gear and nothing changed. Usually when I go from overdrive down to 3, it'll kick down. After work I'll pull the air cleaner and check the injectors/ spray. Yes this truck is a TBI

I would also check the vacuum line to the MAP sensor. I remember when I was putting my engine back together and I forgot to plug it back in and the truck idled very rough and was running very rich. The SES light would come on intermittently too. After connecting the MAP line correctly, the truck ran perfectly and was back to normal. May be something to start with.