I have 94 S420 and having a engine problem.

When I start the engine, it keep die. I thought it was battery but it's not the battery. I clean the fuel pump filter and it stay running but no power when it's running. Also, when driving, transmission gear kick to the nesx gear. When it's kick, you can hear the tire squicking (it feels like somebody is hit you from the back of car).

When I step on a accelator, engine shakes bad and die. I think it's fuel pump but I have a no idea. Is it hard to change piel pump myself? Please let me know what is wrong. Thanks

James

 

fuel pressure?
mass air flow sensor?
sparkplug?
it can be many things. take to mechanic for checking. check transmission oil and linkage too