GM TBI holding revs

[ashhhhh]

Hey all,

I was hoping for some advice and assistance with a problem im trying to sort out. My vehicle is a '98 Lada Niva (stop laughing) and it runs the GM TBI system.

The main issue is that it holds the revs up when shifting gears. What I mean is that you need to wait an annoyingly long time for the RPM to drop before you can release the clutch for a normal gearchange.
It shows similar behavior when revving at a standstill although nowhere near as bad, you can see a video here (ignore bad audio) - https://1drv.ms/f/s!AodQnnnWCBvbu3EuAn__SHx1mzMR
You can see how it kind of pauses at 2000rpm instead of dropping in a linear fashion.

I have noticed no other drivability issues but in case relevant;
- Full throttle seems to cause slower acceleration than part throttle. Full throttle seems to "bog" it a bit.
- The exhaust smells strongly. Not of fuel, just strong exhaust smell. The previous owner as punched the cat out, its a straight through pipe now, im guessing this is the reason for the smell.
- When starting on a really cold day the engine kind of falls over itself for the first 10 seconds or so, seems like excess choke to me.

Any advice appreciated!

Cheers
Ash

[ashhhhh]

My first thought was VSS but I have replaced it without change.
There are no fault codes shown either.

[1project2many]

Is this a new problem with the vehicle? On some vehicles the programming does not allow the engine rpm to decrease rapidly between shifts.

[ashhhhh]

This is a vehicle I've restored and it's been like this since I've owned it.

It could be normal, but I doubt it. It's the same if you are going down hill and take your foot off the throttle. Instead of getting nice instant vacuum braking the car runs away while the revs are held, then it drops back.
It would be a really stupid feature to program that..

[1project2many]

It would be a really stupid feature to program that..

With vehicles here it's done for emissions reasons. Check IAC position to see if it's staying open.

[myburb]

I had a ranger 4 cyl that did it from new. Took it back to dealer several times and was told it was normal. It was so annoying I sold it. My suburban did it somewhat but was able to correct that getting rid of throttle following and a few other changes I would have to refer to my notes to be sure. My feeling was the factory was trying to make up for people who didn't know how to shift properly but that is just my opinion so don't take it to the bank.

[ashhhhh]

Man that sucks, I hope this isn't unsolvable.. Haha
I've replaced the IAC, injector, computer, clean the throttle body, checked for vacuum leaks etc, no change.

I've also built an ALDL cable and bought EFI Live, I've uploaded the data (EFI live v4), and videos of the data if anyone has time or inclination to check it out.
https://1drv.ms/f/s!Ana8t3T9nAw2g29FgCzcjKvVLP3M