1997 SR5 - Throttle Body, IAC, MAF cleaning and plugs
I recently purchased a 1997 SR5 4WD with 263K on the clock. Previous owner couldn't find evidence of a recent timing belt change so that made me nervous, but I was able to buy it right so if I needed to do the TB job I'd still be ok with the price. Over the last few weeks I noticed sluggish acceleration and a very strange bump/shudder/slam around 2K RPM & 50MPH. I was really worried I had a transmission problem so I drove with ECT engaged and the problem subsided. I decided to do some maintenance and started with the following:
MAF sensor cleaning - the bullet/inline style on my particular vehicle
Throttle body cleaning and IAC cleaning
New plugs
The project went well and I ended up cleaning the throttle body due do the excessive amount of buildup I found in the airbox, and air intake hose headed to the throttle body. I had to literally scrape the gunk from the lower portions of the air intake hose. The throttle body was filthy and the IAC looked like it was completely clogged, which is weird because the vehicle seemed to idle just fine and I didn't experience any temp issues.
When I changed the plugs I noticed a significant amount of oil around the #4 plug so I assume there is some back pressure and/or a leaky tube seal.
I finished the project and fired it up. Once I was satisfied that the job was complete I disconnected the negative terminal and left it off for 20+ minutes to reset the ECU. Reconnected the battery and then took it for a test drive - performance was much better at lower RPM and acceleration was noticeably smoother at higher RPM.
All in all I'm happy with the outcome but I still feel like it's a little sluggish during initial acceleration so I'm thinking of doing the plug wires and doing Seafoam or CRC or water cleaning of the intake valves to see if I have buildup. I wouldn't be surprised if I had massive amounts of buildup since I saw so much in the air intake tube, throttle body, IAC and the intake itself. Also considering replacing all vacuum hoses since they're 22+ years old and some are deteriorating.
I'm open to suggestions for other steps to help restore as much performance as possible.