Replaced valve cover gaskets and plentium gaskets drove the truck in the shop but after replacing all gaskets it started for a few seconds and shut down. Checked and found spark weak. It's a 1999 tacoma 3.4 I rechecked everything all connections are pluged up. Any ideas

I'd focus on the Ignition Control Module and Crankshaft Position Sensor. Using an upgraded scan tool, check for any pending codes--it may give insight into the source of the problem.

No pending codes.