The AT was serviced just about 2 weeks ago. I didn't look at the fluid level but the owner says that after he replaced sort of clutch of the AT system the problem arose.

I drove it for about 10 miles and felt quite good about the engine. It picked up real fast but just stayed at 2nd gear. When the engine was heated it started running intermittently and the owner said it is probably due to the fuel pump. I could see the odd sound of the running pump to.

I read the manual it says KAT version 400Es have their transmission shift point retard relay (K29) for heating the catalytic converter so that it reaches its operating temp more rapidly. Should K29 be the suspect for the failure of 3rd gear 2?

Sounds lots of problem, doesn't it? I am in negotiation of the owner about the price. I believe those problems are solvable. This beast is quite rare in here so I want to grab it though I already have a 300E.

Thanks for your response, I will do as suggested once it's mine.