cel Changed Catalytic converter, now getting tons codes and terrible shifting.

[David99RX300]

1999 RX300 134,000 miles. 

About 2 weeks I had my noisy exhausted fixed which was a flex pipe and catalytic converter.  That day I drove back home, I noticed a misfire while on the thruway at high speeds and going uphills. It got so bad, the entire vehicle "choked"  when going up any hill. Changed the spark plugs and ignition coils. I also noticed that my fuel range had drop from around 22mpg to about 10mpg since the catalytic converter was put on.

A couple days pasted after changing the sparks and coils and the vehicle was running fine to my knowledge. Then a strange clicking started in my dash, driver side, behind vent. Read up on it and seems like the air servo thing. Not to concerned, I just dealt with the clicking. I noticed I was still getting terrible gas mileage. Barely 120 miles out of a tank of gas.(average was 250 before Cat change.)

Couple more days have pasted and now I am having much bigger problems and tons of fault codes. 

1. P0125 insufficient collant temp forclosed looped fuel control
2. p0300- powertrain- random/ multiple cylinder misfire detected
3. p0301 -powertrain- cylinder 1 misfire
4. p0753 - powertrain - shift  solenoid "A" electrical
5. p0758 powertrain- shift solenoid"B" electrical
6. p1135 powertrain -
7. p1300 powertrain-
8. p1305powertrain-
9. p1315 powertrain
10. p1320 powertrain
11. p1325 powertrain

This is going to be hard to explain, but when i started the vehicle, it would be fine,Dash clicking still there, but fine at idle. Until I started driving and it would start shifting weird. Bucking and then would stay in a high gear. I would come to a stop and hit gas, but still in high gear, barelllly moving. stopped put it in park, Fine. Put it back into drive, still in high gear.  Stop, turn off vehicle, turn back on, and it is back into 1 gear, and then starts bucking again and does the high gear thing again. I noticed that the when the dash board clicking noise stops, the check engine light go out for half a second and then when clicking starts again, back on. odd. 

I had zero problems before the Catalytic converter. No misfire, great fuel economy, perfect transmission, no dash clicking. Is this the end for this vehicle?

Thanks all who can help. I will be on answering any questions. 

[TrevC]

Hi

I can only imagine that something was disturbed during the fitting of the Cat, may be worth dropping it into another garage for them to check the underside for loose or disconnected wiring from sensors, etc.

Maybe also worth disconnecting the battery and reconnecting to see if it resets any of the systems.

Let us know how you get on with it

Cheers  Trevor