Car is missing and bucking when hot...HELP!

[trbkrb]

Hey gus, looking for a little guidance. My 87 LX 5.0 has started running bad. I cleaned the engine with simple green and a garden hose and replaced the passenger valve cover gasket a couple of weeks ago. Car was running fine right after that, but after a few minutes of driving, it developed a miss around 3000 rpms. This miss became more often until now it is missing every few seconds at idle and the car bucks and jumps under any throttle at all.

It runs fine right after cold start up, and begins missing when I've traveled about 3 miles or so, and then the bucking progressively gets worse. Since it started, I've replaced the plug wires, checked the coil and TPS with other good parts, cleaned the IAC, checked all connections and hoses, cleaned the cap & rotor contacts (both 10 months old).

It is an audible and visible miss at idle, the tach bounces down and it jumps all over the place during acceleration. The only thing that is notable, is that it runs fine on cold start and does not act up until it warms up. So my mechaninc friend thinks that points to something relating to the cold start vs hot settings/ sensors, or possibly some electrical problem that is affected by the heat.

The only codes I have are 44/94 thermactor system inoperative, but I've had that code for the past several months. I plan to change the cap and maybe try to find a good distributor/ TFI to see if that may have some bearing. Any more ideas?

THANKS!

Thomas

 

[jrichker]

TFI is a possiblity, since they tend to fail when they get hot.

 

[GoldenEye]

I had some very bad idle problems a few weeks ago, then it turned into a running way too rich problem and horrible miss. My reader spit out a code 44. I has to ge the car running becuase it was my daily driver so I took it to the mechanic. Turned out to be a shorted wire behind the intake around the 10 pin connectors. They fixed it and car now runs better then ever. Perhaps some water got into a plug, or wire and shorted things out.