Help! Can't figure out what's wrong with my 94 350tbi

[Canadian93ck]

I bought this truck 2 months ago I've put 10,000km on it and still can't figure out what's wrong, it randomly runs like a bag of ****, worse in the rain but even in dry conditions a couple hours into a highway run it will stop holding a steady speed, it will lose it's speed I'll have to drop a gear, it accelerates perfect but then will lose it's speed again, then when I get off the highway it will stall or barely run, just chokes but if I step on it it pulls strong but thats it, sometimes it will drop a gear and the rpms will go up on the gauge but the motor doesn't actually rev up and go for a few seconds after, no one can figure it out Ive done a full tune up, check engine light never comes on and the scanner can't find anything, I tried a new heat gauge sensor, I tried disconnecting the egr and plugging the vaccum line, that helped for a bit I thought then it started doing it again so I'm probably going to replace it, my next step is replacing the coil but it doesn't look cracked or anything and the only other thing I can think of is the computers just messed. Frusterating because it's a strong motor that has lots of power but randomly runs like crap, if anyone has any ideas let me know thanks!

 

[woody80z28]

Have you checked fuel delivery with a pressure gauge when it's acting up? How about the CTS wiring? Get a laptop hooked up and log it.

 

[ChrisAU]

Throttle position sensor malfunctioning at high temps?

 

[Swaggerwagon]

a full tune up including cap/rotor button should be your first step...

 

[Canadian93ck]

Might sound stupid but how do you check the fuel delivery and I it was the throttle position sensor wouldnt at always run like crap and have a rough idle? I found another threa where a guy with a 4.3 that had the same problems but never posted what it ended up being, if I let it idle for a long time it smokes and smells like a rotten cat but I don't think the cats the problem, I feel like it's getting way too much fuel I gotta keep feathering the pedal to keep it going, I havent tried much yet I just want to know what to replace next before I head down a long road of bills

 

[Canadian93ck]

I did a full tune up as well, fuelfilter, cap, rotor, plugs, wires and air filter

 

[ChrisAU]

Welp with our new discount code you could get a TPS from Rockauto for around $15, and what your truck is doing is directly controlled by that sensor.

 

[Swaggerwagon]

Well then, fuel pressure check would be the next step...

 

[Canadian93ck]

Thanks guys I'll let you know how that goes

 

[woody80z28]

If your CTS or wiring is bad it will be really rich. That's another thing to check. If you can datalog it, you should be able to find something.